Does the video url contain the username and password in them (if needed)?

m3u and m3u8 are just text files, if you open any list in a text editor you will see that it's full of links, so yes that's possible. Will it work? that depends on the stream, its format, or if it has any protection, like tokens etc.

VLC has a way to do it. Search it, i cbf

Actually, m3u8 is a text file containing links and codes, which points out the path and order of media data. Problem like cannot load m3u8 may come out.

https://www.leawo.org/tutorial/solved-cannot-load-m3u8-1398.html?qa=1410