Yes, I've read on ongoing HD problems at IS. I only upload 720x486 video clips to them with no problems.

In regards to uploading animations, I think they want a jpeg of the animation in various stages of development/rendering. In other words, one long jpeg with a sequence of frames in it. I know, SS makes it so much easier! That's why I've stayed away from uploading any CGI work at IS. There is a FAQ on there in regards to the details of what they want.