I know I'm humanizing Rakus here but I'd like to think that, when he kisses the tree towards the end of the video, he does so out of gratitude for helping him. :-)
Apparently orangutans do kiss to show affection. And the lips are probably full of nerve endings for foraging purposes anyway. So who knows, maybe he was actually kissing that tree to show some kind of positive emotion, whether it's a kind of reciprocal appreciation similar to what we'd consider "gratitude" for helping him, something associative on a simpler level for making him feel better, or maybe a different, uniquely orangutan emotion that we don't have the words for.
> I know I'm humanizing Rakus here
Out of all the species on this planet, orangutans probably have some of the emotions that are the closest to human emotions. Like, would you expect Ancient Greeks to have emotional experiences that are recognisable to you? What about Cro-Magnons? Neanderthals? Australopithecines? Where do they stop being people with rich inner lives, and turn into animals driven by instinct?
Orangutans are tree-dwelling (semi)social fruit eaters, like we were not that long ago. If you set the Tree of Life to "Zoom to Fit", we'd blend right together. "Humanizing" would be if you were talking about an octopus, a fish, or a protozoan. Different humans at different extremes already experience emotions in vastly different ways; I don't think it's unthinkable or odd that the median individual in such a closely related species might have experiences which we can relate to.
But also he looked to me like he was chewing in the last couple seconds, so maybe the other commenter saying he was just eating ants was right lol.
