That's not exactly the same as just having the audio files though. I've been listening to the lectures on my phone during the train ride to/from work. The reception is really bad, and I have to load the videos at 240p and usually let them buffer for a while. This will be really helpful to me.
I do agree about the asking for permission, but now that sama has commented that it's fine, I'll be downloading this to listen to offline.
He created some value for a few people. Probably wrote a 5-lines-long bash script to download the youtube video, pull the audio out of it, add the mp3 to a repo, commit and push. He's done something nice, so that others won't have to.
You're asking him to ask a few dozen people for permission. Suddenly this becomes a project. And what if one person doesn't see the e-mail, forgets to reply, or it ends up in spam folder? The repo becomes incomplete and far less useful.
I won't use it myself, but I can see why somebody would. When I listen to something on Youtube on my phone and hit the power button to turn off the screen, it pauses the video. It doesn't pause the audio in pretty much any music player app.
Is this how we ask for permission to use someone else's work in the future? Above all, the YC folks are fast -- I bet you'd get a fast reply from Altman if you were to ask before rehosting the content.
I've been happily listening to, and learning from, the lectures by opening the youtube videos and putting them into a background tab.