ActionScript 3.0 :: Skip Intro Then Go Back Error?

I have created a preloader for a video intro, with a skip button. This preloader is loaded inside the index.html file.When the user skips the intro video, he is forwarded to another page. This part works great.The problem is that if you ever go back to the index.html file after you skip the intro the flash file recognizes that the video is already downloaded, because it is partially downloaded because it begins to download before the user can press the 'Skip' button. I imagine this has to do with the fact that a partial file with the same name exists in cache.When the user clicks on the 'Skip' button I close the loader that was loading the video file like this:

loader.close();

Is this the problem? I thought that Flash automatically compared files.Is there any way to compare the file in cache on the users computer and have the file either resume or redownload if the file sizes don't correspond?