His line doesn't look like a set or better K. At least I don't see sets played that way in my games.

Would many players at 2/4 c/c with QJ on that flop?

Could also be KQ, KJ, JT. A pair and a draw seems likely as well.

Does his bet look like a bet strong, fold to shove type of bet? Maybe bet pot is just standard, I don't remember UB and don't play this level. I think I would shove.