A rule of thumb I have heard is, flash and videos in splash pages are for things like movie trailers. In fact they say to avoid intro pages (splash screens) altogether unless you have to.
If you want to addition a movie you might want to add it as a link that the user can click on but not make them have to view it, or click away, on a splash screen.
What is Internet and Web Presence?
http://www.mimsin.com/WebPresence/Wh...-Presence.aspx
related to your question in general,
this URL is a great explanation of why web presence is *huge*
(I am not affiliated with these folks)
-Lesley