Quote - **
Tried to use png and tiff and loose the background
I must be missing somthing here:)**

The alpha channel is what keeps getting included (then ignored). You have to not bother saving it, IIRC (been so long since I had to mess with that setting, I may be wrong, but it's one way or the other that causes transparenting on the background).

Also, animations are different from stills, so in an animation, save it however you like - the codec/format (AVI?) you convert them to will discard all that and come up with its own anyway :)