How could I get a flashing effect for video wallpaper?

I want to set video wallpaper as my backgroun, and I want to have a picture of the T.A.R.D.I.S. flashing. I have a picture of the T.A.R.D.I.S.
that would work perfectly. Could somebody add a flashing effect to it and have it in movie format for me, I would be forever grateful.

I would like it to resemble the “real” flashing effect as much as possible, and around 5 seconds that could be looped smoothly.

The pic