2D first person point and click adventure: animated backgrounds

Hi folks,

I wanna start my first game, and to keep it simple and non 3D, I want to use (animated) 2D backgrounds, like flickering lights, steam, cars driving by etc to make the scenery more alive looking.
I wonder how to go about it: prerendered video that is playing ? I guess there must be a smarter way, since if is an animated video it will probably use a lot of space (RAM/HDD).Cutting up the animation and divide it between animated and unanimated parts maybe ?

Thanks in advance for hints

Emme