Animated gif on dashboard?

A while ago, I was messing around with a gif I had saved from tumblr onto my macbook pro and I somehow ended up getting it to play and loop as a widget on my dashboard. I think this is awesome and I absolutely love that this is possible. But, this was a while ago and I am not even sure what I did to make this happen so could you explain what I did to make it act like a widget on my dashboard? Is it possible for it to be used as a desktop background? How would I go about doing this? THANK YOU SO MUCH!!!!!!!!