It looked to me like the chamois at the beginning had evil intent. It was looking at the little bird (who wasn't even looking at the chamois) and thinking about a taste-test. Then, a whole gang of them started to move down the slope to create a trap for the poor little bird.
It was pretty obvious to me that the first chamois baited the bird in with a worm, and his buddies were hiding behind the rock, ready to jump out and do some serious bird-stomping. Then the bird got her poor feet caught in the wool, and struggled to break free.
As both critters fall off the cliff, the music is covering the little voices of the chamois gang, as they say "tell us when your ready, we'll jump out and stomp her... Hey, where did she go?"
I can see how the clip could be mis-leading, though, and skewed to make it look like it was the birds fault.
