that's funny, i use firefox and that's EXACTLY the problem I have. Apparently it has something to do with embedded .AVI files.
The workaround (using the latest firefox), is to find a page where you have this problem and at the top of the firefox window got TOOLS/PAGE INFO/MEDIA, now a window will pop-up with a scrollable list with 2 collumns ("adress" & "Type"), scroll down the column under "Type" until you find a file that says "Embedded", this is the media. Right click on the file and "Save file as" (your desktop), this download the file to your PC so you can look at it "Manually" and in your own time...