E.g. With "JDownloader".
Is a program with which you can download various files relatively easily.
You simply copy the video link you want to download while this program is open and then it should be visible in the "left collector".
If that does not happen, you can click on the program in the top left corner of "File" and then "Analyze text with links". Since then this link should be in there (otherwise recode) and then press "continue".
Just want to record the current stream and download or save streaming to Twitch?