HLS and DASH: why some videos come in pieces
These two streaming formats explain why "Save video as…" doesn't work on most websites — and how to download those videos anyway.
You have probably tried to right-click a video to save it… and found that the option didn't exist, or gave you an empty file. The reason fits in two acronyms: HLS and DASH.
One video, hundreds of small files
Instead of sending a video in one block, most websites cut it into segments of a few seconds. An index file — an HLS playlist (.m3u8) or a DASH manifest (.mpd) — lists those segments.
The website's player reads that index, then downloads the segments one by one, as you watch.
Several qualities at once
Each video usually exists in several versions: 360p, 720p, 1080p, sometimes 4K. The player switches from one to another depending on your connection. This is called adaptive streaming.
With DASH, picture and sound are often two separate tracks, which must be joined to get a complete video.
What AllVideoDownloader does
- It spots the video's index while the page loads it.
- It offers you every available quality, and the audio alone.
- It downloads the segments of the chosen quality, in parallel.
- It assembles them — picture and sound included — into a single MP4 file, right in your browser.
Everything happens on your computer: the video never goes through our servers.
What about protected videos?
Some services (Netflix, Disney+, Spotify…) encrypt their streams with a protection called DRM. AllVideoDownloader detects these protections and never circumvents them: such content is marked as "protected" and can't be downloaded.