Is it the Dairy Milk advert? I'm sure the answer is usually in small print at the bottom of a page somewhere...
WAIT ! oh god how stupid am I? FFS all along it was staring me in the bloody face ! what a dingus ! It's Jackass 2.
Ok, this has all proved to difficult for everyone, so I'm calling it now. The film was (ba-dum-tish) King Kong. Here's something might be a bit easier :