Thanks for the info here.

I emailed Youtube (following the example from TVC-Videos) and, after a failed attempt, then got it right and got the contact info for the claim holders on 3 of my videos.

I emailed them and got an almost instant reply from 1 telling me that the video is only blocked in certain countries and is unavailable on mobile devices.
I guess that means "NO" to them releasing it.

I'm still waiting for a reply on the other 2.