This is kinda interesting. Earlier this year I took my race car to a chassis dyno to see if the engine was okay (it felt down on power at the previous race). During a run someone noticed a lot of movement in the chain. We video'd it on the next run.
http://www.vimeo.com/1131103
Even though the video seems to show the chain is way too loose, it wasn't really loose when felt by hand. I adjust my chains tighter now.
PS. This is my first video host post. I'm not sure if it's easily viewable by everyone. We'll see ...