My bengal loach did the SAME thing but @ 2x the speed. I found it kind of annoying but I prefer that behavior instead of chasing other fish.
I would put some plants where they normally do the crazy diving/surface swim, so you don't see them.
I was planning to get a 3 oto cats to start with, but I'll wait till after I upgrade the tank, check the cycle wasn't disrupted & have it decorated.
You should make a video of the betta schooling with the oto cats. I would like to see that. My betta seems to prefer lounging around. I'm going to get him a silicone anemone type decoration so he can use it as a couch.