Stopping Background Video in Media Lab

Hello,

I need some help with videos for an experiment in Media Lab.

1) I need to have the background video to stop playing when participants clicked the continue button at the bottom of the page. For some reason, the video keeps playing even after continuing to the next page. Is there a way to correct this?

2) Also, my videos will not play most of the time (using back video since I couldn't get it to play correctly using Movie item type). During one test run it might play, but on the following test runs they would not run.

Thanks for the help!
Rakim