I'm trying to wrap my head around how media player websites work.

This might not be fully programming, but idk where else to post this question

Some video sharing sites uses blob objects to send the video in chunks, instead of letting the browser download in full. Usually there's mpd or m3u8 files that we can use to download the whole video

But some sites don't use those files. They send mp4 chunks, but those mp4s can't be played and seem encrypted.

How is the webpage's video player able to play the video? Is there a decrypter or something in the webpage/video player? Am i able to download all mp4 chunks and run them through some decrypter in the webpage served to me and create the whole video from it?