How to Download a Blob Video (HLS and m3u8)
FileShot Team · 2026-10-04
Why “Save video as” does nothing on some players, and what does work.
You right-click a video and the save option is missing, or you inspect the page and find a source that starts with blob:. Pasting that address anywhere does nothing. This guide explains what a blob video is, how HLS and DASH streams sit behind it, the manual way to save one with ffmpeg, and the one-step way with FileShot.
What a blob URL is
When you inspect a video and see a src starting with blob:, the player is building the video in your browser’s memory from many small pieces. The browser feature behind this is called Media Source Extensions: the player script downloads segments and feeds them to the video element. That blob address only exists inside your tab, so you cannot paste or save it.
Where the pieces come from
Most blob players use HLS (a playlist file ending in .m3u8 that points to hundreds of short segments) or DASH (separate audio and video segment lists described in a .mpd file). To get a normal file, something has to download every segment and join them in order, with the audio.
- Master playlist: an .m3u8 that lists the same video at several qualities.
- Media playlist: an .m3u8 for one quality that lists the segments, often .ts or .m4s files a few seconds long.
- Audio playlist: on some sites, a separate .m3u8 or DASH list carries the sound.
- Encryption key: some HLS streams scramble segments with AES-128 and list a key address. That is ordinary encryption the player can read, not DRM.
Why sites use HLS and DASH
Segmented streaming lets a player start quickly and change quality as your connection changes: it fetches a few seconds at a time and picks the next segment at a higher or lower resolution as needed. It also makes it easy for sites to serve video from many servers at once. The side effect is that there is no single file to save, which is why the browser’s own “Save video as” option is missing or produces nothing useful.
The hard way
- Open developer tools (F12) and go to the Network tab.
- Type m3u8 (or mpd) in the filter box and start the video.
- Copy the playlist address from the list. Pick the master playlist if there is one.
- Run ffmpeg with that address.
ffmpeg -i "PLAYLIST_URL" -c copy output.mp4
If the server refuses the request, it is checking headers. Add the page as the referer:
ffmpeg -headers "Referer: PAGE_URL" -i "PLAYLIST_URL" -c copy output.mp4
This breaks when the playlist URL expires, needs special headers or cookies, or is only requested after the page runs its scripts. Signed playlist addresses often stop working within minutes or hours, so a copied address can fail by the time you paste it.
The easy way
Paste the page link, not the blob, into FileShot. FileShot’s headless Chromium engine opens the page like a real browser, plays the video, captures the HLS or DASH playlist the player requests, downloads the segments, and joins them with the audio into one MP4. If a site-specific extractor can read the page faster, one of FileShot’s other four engines does it first.
| Manual ffmpeg | FileShot | |
|---|---|---|
| Software to install | ffmpeg | None |
| Find the playlist yourself | Yes, in developer tools | No, paste the page link |
| Expired or signed addresses | Fails, copy again | Fresh address captured each time |
| Separate audio | Extra steps | Merged into one file |
| Works on a phone | No | Yes |
Common blob video situations
- Embedded players on news and sports sites: usually HLS. Paste the article link.
- Course and lecture pages: often HLS behind a login. If you need to log in to watch, a server cannot reach it.
- Social video on desktop: many social sites use blob players. Paste the post link; FileShot’s extractors read most of them directly.
What will not work
Streams protected with DRM, such as paid streaming services, cannot be downloaded by any tool. DRM systems such as Widevine, FairPlay and PlayReady decrypt video inside a protected part of the browser or device that no downloader can read. Video that requires your own login is also out of reach for a server. Download only videos you have the right to save.
Frequently asked questions
Can I download a blob URL directly?
No. A blob address exists only inside your browser tab. Use the page link, or the .m3u8 or .mpd playlist behind it.
What is the difference between m3u8 and mp4?
An MP4 is one file. An m3u8 is a playlist pointing to many small segments that must be downloaded and joined.
Is AES-128 HLS the same as DRM?
No. AES-128 HLS lists its key for the player, and ffmpeg can read it. DRM keeps keys inside protected hardware or software.
Can I download a blob video on my phone?
Yes, with FileShot. Copy the page link, paste it into FileShot in your phone’s browser, and download the merged MP4. The manual ffmpeg method needs a computer.
Compare: FileShot vs Video DownloadHelper, FileShot vs Video Downloader Plus. Related: How Online Video Downloaders Actually Work.
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