I bet you crapped yourself when you first saw that messed up boot screen
I've had a look at the gif files you're using and they differ from the originals. The ones you made, each frame has different background properties. If you look at each frame in the original, they're all 320*480 with a background colour index of 199; they all have a black (transparent) background of 320*480.
But the modified gifs have frames which don't have the same sized and colour index backgrounds, and this is the only thing I can see that would cause the problem. When you view them in windows picture viewer, they show up fine; I think it's something to do with the transparency and the fact that the first frame IS the right size and colour but the rest are not.
In fact now that I look at your video again I'm certain this is the case. I know how to fix this, what program did you use to modify the frames?
Edit: Okay maybe I should read posts better, you used Ulead Gif Animator. If you can send me the individual images of each frame I could put this together for you in a way I'm sure will work
"We will suffer any consequence tomorrow, not to feel uncomfortable today".