It looks to me like they might have made a nice gradient or maybe a 4 color gradient on a solid. You could make this in just about any graphic program I would think.
Next it looks like they have some simple shapes that the over laid on top of the gradient, possibly blurred out and with a blend mode turned on.
They could have used a fractal noise, which is used to make a lot of animated backgrounds. The whole background could just be one scaled up with some nice color correction on it.
I'm sure it you looked around this site and others on the web you can find a good tut for animated backgrounds in AE. You may also want to check out the ones that come with AE as a starting point.
if you build this for a commercial, and your new to "it" (AE? Video? Commercials?) and you need a tutorial for this (simple stuff), you should maybe have enought TIME to learn and not be an a deadline somewere near!
or you should get someone that helps you - but i don´t see it in forum post´s. get someone who shows you the stuff you need in real life!
Ad a solid, color it.
Ad some grafik stuff, ad blur, ad movemend.
Ad a new solid, other color, mask it, feather the mask.