One of the few good features of the new Studio Beta is the copyright detection system, which automatically detects other videos that contain copies of all or part of your videos. Then it gives you options to ignore the match (if it's clearly Fair Use or an otherwise authorized use of your content), to send a message to the person who uploaded the copied video, to give them a 7-day warning to voluntarily delete the video before YouTube takes it down and gives them a copyright strike, or to issue an immediate takedown of the copied video.
Generally most of the copies of my videos that I find are from spam-bots who re-upload one of my videos and put a spam link on it, in which case it's not worth bothering with the 7-day warning because there's probably no real person there to respond to it, so I just issue an immediate takedown. But if the channel does seem to be run by a real person, then I give them the 7-day warning.