Video not visible - why?

Hi there -
I’m a Flash Newbie and I need some help.
I have the problem that a video I imported in Flash is visible on my pc but not on any other. I converted the video into the flv format und dragged it onto the scene. so far so good.
I created a folder which includes the main swf as well as the video in the flv format. Since this is a University project, I sent this folder to a professor and he could not see the video. I’ve tried it on any other pc - wouldn’t work either.
What am I doing wrong?

Thanks in advance for your help!
Franni