The guy who stole the video is still using it, still making money, and lying about it. The question of integrity comes from how much you value the videos that you create. If you don't shut down the "scum bag" that stole you video, i don't think you value your own product very much. The guy was a "scum bag" untill money changed hands. Is there a part 107 violation either way?
Cheers
The difference is he is NOW using with the original owner/creator's consent. From that point on everything else is a moot point really. The video was briefly taken down by YouTube until the conflict was resolved by the OP and the YT Channel owner. After that exactly how is the OP's integrity jeopardized? It is not.
On to point #2:
A) If the "scum bag" didn't make the flight he isn't liable for the Part 107 so long as he didn't solicit the flight originally.
B) If the original creator flew as a hobbyist and later sold the video then no Part 107 is needed. It's 100% about the INTENT at the time of the flight and not about $$ changing hands. The FAA clearly stated that a hobbyist can indeed exchange their footage at a later time for compensation so long as the original flight was completely within hobbyist/Part 101 guidelines.