This is what he said:
"Scientists aren't exactly sure what type of shark it is and people have said it could be the long-thought-to-be-extinct megalodon .... but another theory is that the footage caught a very large, very rare Pacific Sleeper Shark. Sleeper Sharks can grow to lengths of 23 feet, so even if it was a Sleeper it would have been the biggest and longest of its kind to have ever been spotted."
This is what is wrong with the video. There is a completely factual explanation for the dead killer whale, for the dead beaked whale, for the footage of the sleeper shark - but he makes out that they are "Mysterious & Unexplained" and could actually be sea monsters or megalodon when they quite obviously are nothing of the sort. A sleeper shark that big (if it really is as big as it appears to be) is really cool - why bring nonsense into it? "People have said it could be megalodon" - the only people who would believe it to be so are people who know nothing at all about sharks, and the suggestion shouldn't even merit repeating in a video which could have been much better.
He should have made the video as "top 5 "mysterious" sea creatures explained" or something like that. Would have been more interesting overall.