For the intro, just put it to 640x480x32, which is supported by modern systems, and the intro is a bit smaller but still big enough to see. At this size the pixels are already big enough to poke your eyes out.
I managed to do something for you. See this post. In short, I made an alpha version of the game, update to that and you should be able to get your movies (almost) full screen. Let me know if it works for you.