I can't ID the animal from this clip. Unfortunately, there is not a single frame where the meral spots are visible. Are they white or yellow. I do think that I can see some shell disease starting on the back of the animal.
Shell disease starts as small patches of brown discoloration of the cuticle. Eventually it can develop into severe erosion and even holes. We don't know what causes it, but certain species seem more prone to it, particularly in older animals that molt infrequently. O. scyllarus and Gonodactylus ternatensis are particularly prone to this disease. If it has not progressed too far, it often clears up when a molt occurs and the old infected cuticle is shed.