How it works, what you get, limits
What it does
Keep the soundtrack and drop the picture.
How to use
Pick video or audio, choose a container, download. No audio track fails.
What you get
M4A or WebM. Compress if you need the whole video. MP3 is not guaranteed.
Options and comparison
Output container.
This is extract/remux, not a studio MP3 encoder.
Limits
MP3 encode is not promised. No audio track fails.
FAQ
Always MP3?
Not promised. Typical output is M4A or WebM.
No audio track?
It fails. This page drops the picture and keeps sound.