Unique mp4 caching example

I’m making a website that will have an intro. I’m also making a countdown to the launch of this website. Both, the countdown and the website will be on different domain names (but probably on the same ftp folder).

Is it possible to begin pre-loading the intro.mp4 (and complete it) on the user side (he’ll have to have the window open), when the countdown is near done, and then when the countdown ends, and redirects the user to the main site, just load the intro from the users cache?