(Flash 8) Video problem - no picture, only sound

See http://www.adkiivi.fi/flash/testi/. Refresh a few times, and you can see that sometimes the video doesn’t load, altougth the sound works everytime.

I tried rebuilding the system from scratch, following a simple video tutorial, but ran into the problem again when setting autoSize = true;, thereby seemingly isolating the problem. I then tried specifying the autosize when the loading of the video is completed, but it didn’t solve it. The loading seems to be indeed completed succesfully, as you can see from the red text on the upper left corner which changes when the completion event occurs.

Strange thing is that this problem doesn’t seem to occur when using another video, though I’m not absolutely sure about that. I also tried moving the video from an external server to the same as the website.

So now I’m out of ideas. Any help would be greatly appreciated.