From just now, I went to gmail.com and created a new account without entering a phone number or email address.

I then went to Youtube and uploaded a video.

I signed out, then in again. Google asked for a number and recovery email, but let me press "Done" without providing one.

I'll sign in later from a different IP, and see what happens.

Edit: I've come across [1], which says a phone number is required to upload videos longer than 15 minutes to YouTube, or in some cases to upload anything.

[1] https://support.google.com/youtube/answer/171664