I.. couldn't make it through either one of the videos. Since I couldn't, I can't fairly judge the theories.
What I did want to say though, is that the moment a theory relies heavily on the reading of otherwise platonic seeming actions as evidence of romantic undercurrent... it hurts it more than helps in my eyes.
I don't have a horse in any of the shipping debate personally. But I tried to watch the vids because I didn't really see where the theory came from in my own viewings of the show, so I was wondering what I missed. And it appears that what I missed was a bunch of stuff that could just as easily be signs of a close platonic friendship as it could be of a romantic one.
Whatever direction they go with any of the romantic relationships in RWBY, I hope that the writers progress them clearly and logically, rather than fence riding with generic friendliness then going with a last minute paradigm shift.
The buildup issue is itself somewhat iffy. Arkos had buildup from their first meeting that really only came to fruition right before the end. In retrospect, it was pretty obvious from the start, but could have been passed off as friendship if only a few events changes. At best, the true romantic stuff really only appeared in a few episodes.
If they wanted to do bumblebee, I think they would only need to spend a few episodes/scenes on it, because doing such would allow the viewers to re frame all those previous moments as romantic buildup. Not that viewers aren't already doing that.
Also, I have no house in the race here (though, long live Arkos's memory), but man do I love the fandom nicknames for pairings. Arctic ocean, ladybug, Lancaster, bumblebee, white rose, north pole, communism, etc. They are all so catchy.