You have to get the distinct impression that this couple of cats are very close emotionally. I have a sense that they are brothers but the person who uploaded the video does not tells about their relationship. Although their relationship is an important part of the video.

They think alike. Then it goes a little bit wrong once they get to the top of the wall. Ginger-and-white tabby tom lands on black-and-white bicolour buddy and he is not quite sure how to get off or that is what it initially looks like.
It seems to me that the cause of the tangled end is because the black-and-white lands on the end of the wall first because he is nearest the left hand wall. He does not allow his buddy the space to land. That’s clearly the cause.
I think ginger buddy knows what to do to disentangle himself but does not want to do it because it is pleasant for him as he in close contact with his buddy. He gets off in his own time. Some people might see a sexual connection here but I don’t. I just see two, probably male, cats in harmony together, psychologically, which results in them being together physically on this occasion. I can see them doing other things in a similar fashion.
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Could be true. Sort of guesswork.
My thought is they are in a precarious position and want to take care for them self and the other not to fall back down as they negotiate the next moves necessary to remain up there. Obviously it took teamwork. So cute, so cat-like, and so bonded pair-like. I have a pair who think and act alike too.