This 'use a condom' commercial by DLKW is super well directed, and I love the 2 (two!) scenes where the girl sucks up her own vomit - genuinely haven't seen that before - but something about the ad bothers me.
I think it's this: there's no reason why the ad should run backwards. Compare with a legit use of the device - an old ad for BT that showed an engineer 'unsnipping' phone lines because thousands of people were 'coming back' to BT.
Anyway, it's rude to criticise without being constructive. So here's how I would have constructed the ad: there's a great visual parallel here between the alcohol-induced vomit and the pregnancy-induced vomit. That tells the whole story. Put the first one at the beginning and the second one at the end, and suddenly you've got a structure that makes sense.
My version's better, right? I would put it together myself on iMovie, but I haven't got that much time on my hands.