Same here, I declined and got "virtually killed", no more playlist etc. Another short story. helped someone unknown become really famous. Got a DMCA takedown notice on all my videos, that's the "thank you". The best part is that the file I uploaded had no license, nothing. As said that artist was completely unknown. I thought about fighting back, then just said.. f* off.. I'll wipe and shut this account down. Not worth it.. She had barely 100visitors or less in total for years, had to delete her vids with some hundred million visits..
Turns out she was completely wrong about having lost her data, the UI was just confusing in such a way that she thought she had. Don't get me wrong, that kind of confusing UI is very much Google's Problem, but "confusing UI" and "lost all my videos" are _very_ different in magnitude.