Tbh, I thought that move was a bit strange by LH and perhaps he should have been penalised for it, but from what that clip showed (I didn't see the whole race) it looked as if Vettel wasn't looking where he was going, and that he was going quite fast, even accelerating maybe.
Distracted by Webber or LH is beside the point, it was wet and visibility was crap which means he definitely should have been looking at where he was going, and he should be penalised for sheer, mind-boggling ignorance.