Maks said that he and Brandy had watched some show together and that ever since it had been a running joke for them to smack each other on the bottom as part of it. Plus, Maks smacks others on the bottom, look at Tom. I think he found that CA took it upon herself to smack him like his mother would have done that made him so angry. She wasn't doing it out of jest, she was trying to put him in his place (or at least that's what I took from that). I also thought that CA was out of line.
If he and CA had that sort of friendship (like he and Tom do or evidently like he and Brandy do) then that would be one thing. But they don't. I think that's why he was so mad because he felt it was uncalled for and rude and I agree.
There is showing things in the rehearsal footage and then there is twisting it, taking it out of content, and adding sound to it to make it seem even worse than it was. Are they trying to completely tarnish his reputation? His reputation is his livelihood. He has every right to be angry if they are showing things that could cost him business especially if that is not the way these things happened in reality.