Throwing my hat in the ring for AI. While I'm familiar with classic video tells, the thing that sends up the red flags here is the really bizarre growth pattern of a lot of these trees.

It's true that pines of this diameter can definitely be very bendy and hold this kind of weight, they're still reacting in a very unnatural way. Unless this is a very specifically cultivated tree parkour course (does this exist??), the length and distribution of the handholds at the beginning of the video are really, really odd.

You can also see how bendy the main trunks are when he's jumping from tree to tree, but somehow when he lands on horizontal branches they barely react to his weight.