Well, actually, insert that question in google and you get so many hits that offer you a solution.
I’ll give you one link to a site that allows you to rip from YouTube but the rest you have to dig up for yourself if you don’t mind.
(This one can also rip audio only)
I can wire my software dvd player into a wav recorder through jack on linux ubuntu studio.
Saves ripping files or analogue wiring.
Wiring a DVD player into you mixer is easiest… then whenever your watching a film and think…
“i could sample that”… you’re already wired in.
Cubase SX or was it Nuendo? had video in it, i think renoise would connect up to that.
You could just record the audio directly, as opposed to downloading the YouTube video (or ripping a DVD) and then having to strip the audio and encode it.
I have a Mac and I use Audio Hijack for this. It lets you select what application to record the audio from (Safari, DVD Player, etc.). And when I was using a PC I think I used Audacity. They’re both free. (Yay!)
Also, from limited experience, I agree with the above suggestion to use the Vixy desktop application. I’ve only used the online version and it was sloooooow.