I have dealt with fraudulent Youtube copyright claims, it's a long and annoying process. First, you have to file a dispute, which typically the claimant will automatically reject, and then you have to escalate to a DMCA counternotice, which will take the video offline for a few days to give the claimant a chance to respond. In my experience, the claimant will drop the complaint at this point, but you're theoretically opening yourself up to legal action by sending the counternotice.