That was funny.
There's no way, in my mind, that it was a setup. Sometimes people get caught up in what they're doing and just forget to do the simplest things.
I believe there are a couple of similiar vids somewhere on this site. The only problem with them though, is they cut out the split second they get caught. This one here went on for a couple of seconds at least. Not sure if anyone knows about the ones I'm referring too, or whether anyone has a link to them.