Well, if you reload a website, then Flash needs to check if every part it's going to use is loaded. Whether you're talking about main swf itself, an external swf or an flv or other video file, it's always wise to make sure that the file you want to show is actually loaded (streamed flv is an exception). That's the whole point of preloading, but when your file is already loaded, it's in cache, then your preloader won't actually appear.
I don't know if I get your point to be honest...
If your movie is being loaded everytime you reload your website, it shouldn't, because the movie should be already in the memory. When you call a kind of load method in Flash, it always checks cache for already downloaded files.