Web page properties are showing 100x75 here, at 420KB like the others have said. You are right it should be an animated .gif file, .bmp does not support multiple frames. So if the one on your computer has saved as a .bmp file then it is only the first frame of the animation, which explains why it looks so small to you
Oh right. But whenever I save a picture, it always saves it as a bitmap, and seems like ava's don't allow you to upload bmp's as your ava (I used a link to make that animation my avatar). Why does it always save it as a bmp and how can I change that?