There's something mesmerizing about thousands of tiny ball bearings, as you can see in this art installation "Wave of Matter" by Helsinki-based designers Tommi Grönlund and Petteri Nisunen. The duo created a motorized platform that tilts from one side to the other, which results in a landslide of the ball bearings.
Probably lots of tiny balls moving around randomly creates just the kind of consecutive frames where you cannot predict the next frame by sliding and stretching the previous frame. Hence there are huge differences between frames, and you don't get enough compression to transmit full frames within the bandwidth budget that vimeo provides.