In my web site, I have a frame called main_frame, and a frame called top_frame. Top frame has two images inside it (to the user they are buttons - called screen shot, and video clip). What I want to do is this:

when a particular file loads into main_frame, I want the specific videos and screen shots according to the page in main_frame to be shown when the user clicks on the images mentioned above. Any ideas at all on how to do this would be appreciated.

Thanks in advance,
Gemma.