Can on an animate background in Presenter?

My boss showed me a web presentation that does not appear to have been created in Articulate, and it has a very nice animated background. Just patterns and graphics fading in and out, but a very nice effect. The effect is on very nearly every slide.

I can do something similar on each slide using the standard PPT animation effects, but building more animations on top of a base of 20 or more animations, seems cumbersome and likely to fail.

Is there a way to do this in a Master Slide?

In the past I could not get animations on a Master Slide to work for me. I tried again this morning and it still did not work. I built an animated gif and dropped it on the Master Slide but that didn't work. Ran fine in PPT, but continuously showed the first frame of the animation after Published.

Any ideas will be appreciated. Thanks, JP