I have a feeling that the best way to go about this would just be to cause YouTube (well, Google) grief about this every day until you get something out of them -- though I'm not sure what to suggest in terms of gaining initial traction.
Do you have an archive.org (or similar) archive of the channel page(s)?
I never even thought of waybackmachine. I just checked and it said there was a pull from the 29th of January... I got excited too soon though as I loaded it nothing loaded.
For now the videos are still lost... Thanks for trying though
EDIT: Actually I was able to load the page after a long time but none of the videos seem to salvageable (they can't be accessed or downloaded just get errors). https://web.archive.org/web/20210129101353/http://youtube.co...