Okay, I just watched it (thanks for the PM Forma, I stupidly didn't even think to click on the news article.)
For the first few seconds I really didn't see anything terribly wrong, but then he very rapidly escalated the whipping way beyond acceptable. And the profanity and verbal abuse as well, just so totally unacceptable. Also, she's 16, and really corporal punishment is out the window at that point I should think, unless you are just being abusive (*).
I do want to disagree with some about the comments the mom made, though. Watching the video, I am really getting the impression that the mother was trying to mitigate it as best she could and was putting on a show for dad. Notice that once mom got the belt, the kid only got one more whipping with it. Honestly think mom was doing what she could to stop it and just had to make dad think she was being stern. Could be wrong, but...what else could she really do to end it?
(*) Got slapped once when i was 16 by my mom. Was having an argument with her and I hatefully and callously called her an old hag. *Bam* instant, instinctive backhand right to the face. Mom started crying and whatnot cuz she'd hit me and I had to tell her it was okay, I deserved it.