i used to do it by doing a search in the internet cache files eg. some sites wont allow you to download pictures witha java script but the pics are in the cache
say john.jpg is a pic ona site so in your cash it will look like john[1}.jpg or something like that, same for video clips look in the cache for video type extentions like mpg or wma avi etc , also on the page where the video is click on view page source read the html and it will give you the name of the clip , this will shorten your hunt in the cache.