A small helper app is needed to run yt-dlp on your computer.
Download and run the installer:
Download for WindowsRun this in Terminal:
curl -fsSL https://raw.githubusercontent.com/user/yt-dlp-extension/main/install.sh | bash
Run this in your terminal:
curl -fsSL https://raw.githubusercontent.com/user/yt-dlp-extension/main/install.sh | bash
Close and reopen Firefox so it detects the native host.
You'll see a Download button next to Share. Click it to pick a quality and start downloading.
yt-dlp and ffmpeg will be downloaded automatically on first use.
Browser extensions run in a sandbox and can't execute programs on your computer. To actually download videos, the extension needs a small helper app (called a "native messaging host") that runs yt-dlp on your behalf.
This is the same approach used by password managers like Bitwarden and KeePassXC, and by other download tools like Video DownloadHelper. It's a standard, well-supported feature of Firefox's extension system.
The helper app is lightweight and runs only when you click Download. It doesn't run in the background or start with your computer.
Yes. The entire project is open source — you can inspect every line of code yourself. The helper app does exactly two things: it downloads yt-dlp and ffmpeg from their official GitHub releases, and it runs yt-dlp when you ask it to download a video.
It doesn't collect any data, doesn't phone home, and doesn't install anything outside its own application folder.
If you don't trust the pre-built executable, you can build it yourself from the source code. The instructions are in the project's GitHub repository.
The tool itself is legal. In 2020, the RIAA tried to take down youtube-dl (the project yt-dlp is based on) using a DMCA claim. The Electronic Frontier Foundation successfully argued that the tool doesn't circumvent any digital protections — it accesses video the same way a browser does. GitHub reinstated the project and created a $1M developer defense fund in response.
It does violate YouTube's Terms of Service. YouTube's ToS say you may not access content through means other than the video player itself, unless YouTube explicitly provides a download option (like YouTube Premium). However, violating Terms of Service is a breach of contract between you and YouTube — it is not a criminal offense. The realistic consequence is that YouTube could terminate your account, though enforcement against individual users is extremely rare.
What you download matters. Downloading copyrighted content you don't have permission to use is copyright infringement regardless of which tool you use. Downloading Creative Commons-licensed content, your own uploads, or content where you have the creator's permission is fine.
This extension is a neutral tool. How you use it is your responsibility.