hi Eli
basically, they should peak wherever the delivery specs tell you they should peak … you need to check with the broadcaster you are delivering to.
that said, if you are just creating your own master, for submission to multiple broadcasters, then my suggestion would be maximum peaks absolutely no higher than -6db
but I don’t edit music videos so my advice may be off … hang about, and I’m sure others will jump in with better targetted advice
best
Andy