TIMBO13 The first time the success page loaded for me, the movie loaded and played fine. Playback seemed ok on my 1ghz iBook G4 but slowed down the rest of my system pretty badly for such a small sized movie without sound.
But as I commented earlier, after closing that browser window, it promptly crashed Safari. Thinking it might be a once off, I loaded Safari back up again and tried the success page again. This time I got the same error as you (""Video playback couldn't be set up").
As I investigated further (in my previous comment) I found it to be even more buggy and unstable... I have uninstalled it now and sticking with default quicktime and VLC.
(Version 6.5)