# YouTube Download Slow or Throttled? Causes and Fixes

Source: https://b-roll-6hk.pages.dev/troubleshooting/youtube-download-slow/
Published: 2026-09-25
Updated: 2026-09-25
Author: Ema Zamboni, video editor (https://b-roll-6hk.pages.dev/about/)
Section: Troubleshooting (https://b-roll-6hk.pages.dev/troubleshooting/)

**In short:** Slow YouTube downloads usually come from YouTube limiting a request, an outdated yt-dlp or a slow network path. Restart B-ROLL so yt-dlp updates to the latest nightly build, then retry. A ProRes or DNxHR file also takes time after the download: that is the conversion, which uses every CPU core, not throttling.

## Why are YouTube downloads slow?

YouTube downloads slow down for three reasons: YouTube serves the stream slowly, yt-dlp is out of date, or your own network is the bottleneck. Throttling is the first case: YouTube sends the data slower than your connection could carry it.

yt-dlp has an option built for throttling. The [yt-dlp README](https://github.com/yt-dlp/yt-dlp) describes `--throttled-rate` as a minimum speed below which throttling is assumed and the video data is re-extracted. The [yt-dlp FAQ](https://github.com/yt-dlp/yt-dlp/wiki/FAQ) adds that YouTube throttles any request with an HTTP chunk size above 10 MB.

An outdated toolchain is the second cause. As of September 2026, the yt-dlp README says a JavaScript runtime such as Deno is required for full YouTube support. B-ROLL installs Deno on first launch, unless an ffmpeg was already on the Windows PATH, in which case TOOLS shows `JS runtime: missing`.

The table matches what you see on a B-ROLL card to the likely cause and the fix.

| What you see | Likely cause | Fix |
| --- | --- | --- |
| Low live speed on every video, far below your connection | YouTube throttling the request, often because yt-dlp is out of date | Restart B-ROLL so yt-dlp updates, then **↻ retry** |
| Low speed on every video and `JS runtime: missing` under TOOLS | yt-dlp cannot solve YouTube's JavaScript challenges | **Reinstall tools**, then retry |
| Low speed on one video, other videos at full speed | YouTube serving that one video slowly | Retry that card later |
| Slow in B-ROLL and in a browser speed test too | Your network: another transfer, cloud sync, weak Wi-Fi | Clear the network path, then retry |
| Download finished, card says `to convert` or `converting…` | ProRes or DNxHR conversion, not a download | Wait: the conversion has its own percentage |
| Clip card shows a percentage but no speed | Normal: clip cards never show a speed | Watch the percentage climb |
| yt-dlp error line with HTTP Error 429 | YouTube blocking your IP address for overuse | Stop and try again later |

> **Careful:** Download only footage you have the right to use: your own uploads, Creative Commons, licensed or permitted material.

[Download B-ROLL for Windows](https://b-roll-6hk.pages.dev/download/): free, Windows 10 and 11 today, macOS and Linux planned. No account, no ads.

## Is it throttling or the ProRes conversion?

A slow ProRes or DNxHR export is transcoding time, not throttling. B-ROLL first downloads the best streams into an MKV master, then ffmpeg converts that master into a `.mov`, one file at a time, on every CPU core.

Read the card state to tell the two apart. `downloading` with a live speed means data is still arriving from YouTube. `to convert` and `converting…` with a percentage mean YouTube's part is done and your CPU is doing the work. The log marks the switch with `Transcoding to DNx (.mov): source 1920x1080 8-bit. This can take a while.`

Conversion time depends on your CPU, the resolution and the frame rate, so a faster connection cannot shorten it. The output is also far larger than the download: B-ROLL's own estimate for DNxHR SQ is 124 Mbps at 1080p 29.97 fps, or 930 MB per minute (124 Mbps x 60 s / 8 bits per byte). The [ProRes and DNxHR file size per minute](https://b-roll-6hk.pages.dev/formats/prores-dnxhr-file-size/) page has the numbers for every tier.

Ema Zamboni built the conversion because 4K60 AV1 footage from YouTube was heavy to play back in DaVinci Resolve. Conversions have their own queue, so the next download starts while the previous file converts. The tier rules are in [download YouTube videos in ProRes or DNxHR](https://b-roll-6hk.pages.dev/features/youtube-to-prores-dnxhr/).

## How do you speed up a slow YouTube download?

Speed up a slow YouTube download by updating yt-dlp first, then ruling out the tools, the video and your network, in that order.

1. Close and reopen B-ROLL. At every launch it updates yt-dlp to the latest nightly build; **Force update yt-dlp** in the sidebar's Advanced panel does the same on demand.
2. Read TOOLS in the Advanced panel. If it shows `JS runtime: missing` or `ffmpeg: missing`, click **Reinstall tools**, which downloads ffmpeg and Deno again.
3. Click **↻ retry** on a stopped or failed card. The download goes back into the queue and yt-dlp requests the video again.
4. Download a different video. If it runs at full speed, the slow one is a single-video problem: retry it later.
5. Run a speed test in your browser. If the browser is slow too, pause other transfers and cloud sync, then retry.

To get one urgent file sooner, click **⬇ download now** on its queued card. B-ROLL moves it to the front and pauses the running download, which resumes afterwards. Pause keeps the partial file, while Stop deletes it, so pause when you plan to continue.

## Do clip downloads take longer than full videos?

Clip downloads move less data than a full video, but they read the stream differently, so a clip is not always faster. B-ROLL passes your in and out points to yt-dlp, which uses ffmpeg to fetch only that section.

Clips from deep inside long videos used to stall while ffmpeg sought through one large stream. B-ROLL now prefers YouTube's HLS streams for clips, which fixed those stalls on Ema Zamboni's own downloads. The stream picked for a clip can therefore differ from the one a full download of the same video gets.

A clip card shows no speed: its percentage comes from ffmpeg's position against the clip length. The **Exact frame cut** option in Advanced options re-encodes around the cuts, and the app itself labels it slower; the default fast cut snaps to keyframes and skips that step.

## When should you just wait?

Wait when the card is still moving: a percentage that climbs, even slowly, or a conversion in progress finishes on its own. Stop instead when yt-dlp reports HTTP Error 429, which the [yt-dlp FAQ](https://github.com/yt-dlp/yt-dlp/wiki/FAQ) says means the service is blocking your IP address because of overuse.

A fix can also be one day away. As of September 2026, the yt-dlp README says its nightly channel publishes shortly before midnight UTC on any day the code changes, and B-ROLL picks up that build at its next launch.

A card with no movement at all is stuck, not slow: [YouTube download stuck at 0% or 99%](https://b-roll-6hk.pages.dev/troubleshooting/download-stuck-0-or-99/) covers it. A card that fails with "YouTube blocked this (HTTP 403)" is a refusal, handled in [fix HTTP Error 403 Forbidden on YouTube downloads](https://b-roll-6hk.pages.dev/troubleshooting/http-error-403-forbidden/). Every other error is listed on [YouTube downloader not working? Fixes for editors](https://b-roll-6hk.pages.dev/troubleshooting/).

## Frequently asked questions

Q: Why is a 4K ProRes conversion slow?
A: A 4K ProRes conversion is slow because every frame is re-encoded into a far larger intraframe file. A 3840 x 2160 frame holds four times the pixels of a 1920 x 1080 frame, so the encoder does four times the work per frame. B-ROLL converts one file at a time on all CPU cores, and the card shows the conversion's own percentage.

Q: Can B-ROLL download several videos in parallel?
A: No. B-ROLL downloads one video at a time from a queue you can reorder. Clicking download now on a queued card moves it to the front, pauses the running download and resumes it afterwards. ProRes and DNxHR conversions run in their own queue, so the next download starts while the previous file converts.

Q: Does B-ROLL show the time remaining?
A: No. B-ROLL shows no time remaining for downloads or conversions. A full-video card shows a percentage, a progress bar and the live speed, for example 5.0MB/s. A clip card shows a percentage but no speed, and a conversion shows its own percentage, separate from the download.

## Sources

1. [yt-dlp wiki: FAQ](https://github.com/yt-dlp/yt-dlp/wiki/FAQ)
2. [yt-dlp README on GitHub](https://github.com/yt-dlp/yt-dlp)

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B-ROLL is a free, donation-supported desktop YouTube downloader for video editors: it downloads videos, clips, playlists and channels, converts them automatically into edit-ready ProRes or DNxHR (or saves MP4, MKV, WEBM or audio), and includes built-in trimming, subtitles and automatic creator credit files. Part of [YouTube Downloader Not Working? Fixes for Editors](https://b-roll-6hk.pages.dev/troubleshooting/) on the B-ROLL website. Download B-ROLL, free for Windows 10 and 11 (macOS and Linux planned): https://b-roll-6hk.pages.dev/download/