Animated Background

I am quite new to blender but I have gotten through some tutorials and I am now starting my own animation to put on avi footage. I am currently animating eyes to pop out of someones head in a cartoony style but i was wondering how I may go about putting my avi footage into blender as a background footage and use it as a reference to where to put the model instead of rendering, importing etc. My second question is how do I render a model or animation with an invisible background for easy editing.? Thanks in advance! :eyebrowlift:

I think the easiest way to get a video in the background (although not the most flexible way) is to simply put a plane in the background and apply an image texture to it. Then load a movie into the image texture.