Why do cats puke so often?

This morning I found the remains of a rat on my lawn. This is not unusual, my cat Bear Grylls is continuely doing his bit to keep plague at bay. However this time he had also puked alongside the remains. This made me realise that cats puke often. Somebody else realised this too and put together this video. The clips are gathered from all over the internet, who puts videos of their cat puking on the internet?

Via Reddit.