I have created several video clips, for my other tables, and I have always used the hologram method, the textures if they are at the power of 2, it is much better for FP, because it is easier to load them in less time, if they are not at the power of 2, FP, it takes a lot more time to load them....
I tried also this, that if the textures are bigger the more resources it takes from the pc, so either always opted for 256x256, then there is also the fact of how many textures are loaded in "texture manager", this also takes resources, but I seem to understand that in "GIF", maybe this is a minor problem.
obviously, the size of the power 2, is based on what kind of object is applied, I'm talking about measurement, for a great visualization, here I quote the trick that George says, if you have a 1024x256 rectangular object and make a 256x256 square video-clip, FP automatically inserts the movie on that object without loss of resolution, I tried this too, but the textures must always be power2, in order not to have loading problems
I would also be interested in making some video clips (for batman 66) in "GIF", to see the difference between a hologram, and the loading time of FP, but I didn't understand how to do it
EDIT:
there is also another factor that affects, if you have a video-clip, let's put the case of 100 textures or frame, obviously at power 2 of 256x256, the size is 2MB, there is also a way or a possibility to reduce the weight, a few KB, this also helps FP