I have completed the new briefing animation. In doing so, I found out that there's a memory limit for animated textures. It seems to be around 512 KB or 1 MB, but I didn't look into it further. The texture set in this animation is 28 128x128 8-bit bitmap images totaling 477 KB. The previous 256x256 versions took up 1.90 MB and only played half the images unless I replaced some of them with smaller versions. This doesn't explain how I got an 8 MB monstrosity on another animation, but I won't complain about that one.
The face looks less green in-game. I might release this for the public soon if any of you want to mess with it, but note that the default briefing images cover it. You will have to either change the image or move the animation (I can do that for you).