Well, if his video came out first then yea, they straight out copied the entire scene. It's not even about the fight sequence itself, it's the fact that they even copied the camera angles. From a moral perspective, if the creator of the video was not at least given some recognition for this that is wrong on so many levels. After all I thought that was one of the best scenes in the movie. BTW, I too am a huge fan of DC animations. Now, can he sue? I don't know. I have very little knowledge of the rule of law and copyright. But can something like this be copyrighted? I'm always at a loss on things like this because, like the dance moves in Fortnite, how does one copyright dance moves when those moves are often combinations of other dance moves. Sure, you can claim you created it but if you used a dance move from someone else wouldn't that be hypocrisy in a way? Take for example the guy who plays Carton on Fresh Prince. He may be claiming he didn't mean it as an admission of stealing but he did say on video that he stole his Carlton Dance from 2 other artist and simply combined them. Android and iOS are in a constant battle to see who can copy each other better but they rarely sue each other because as long as they don't use the same tech they can't copyright the feature itself, only how its implemented. I figure dance moves and thus fighting sequences have to fall under the same concept.
I think I made this extremely complicated but in essence I believe DC did copy his fight scene, which is obvious, but I don't now if he has a legal standing since fight sequences are based on martial art moves you learn that you simply put in a specific order, something anyone can do and thus the potential for another fight scene to look the same or similar is possible.
It's straight up lifted for sure, but I don't think you can copyright coriography can you? It seems like DC just needed a video reference from some small youtuber who wouldn't notice (they hoped) and thus, not have to pay any royalties or commissions so they can pump out some animations. But it's pretty blatant.
He'd have to consult a lawyer because that's a tricky one. I've used poses from one thing, and placed them in another thing. Dance and fight moves are a bit differant because of moves and timing etc, so it would be interesting to see how that would stand legally, or if it would fall under fair use and reference.