It took a long time to reverse, but I think the vimeo toolbar (on the bottom) may have had an effect. I realized that it was covering up a small portion of the video, and about 10 seconds after I moved my mouse (s.t. the toolbar disappeared), the box reversed.
The flashing of the image seemed to affect my perception, almost each time it flashed the cube appeared to reverse
It took a long time to reverse, but I think the vimeo toolbar (on the bottom) may have had an effect. I realized that it was covering up a small portion of the video, and about 10 seconds after I moved my mouse (s.t. the toolbar disappeared), the box reversed.