This has been proven false. They're just trailers.
http://www.joystiq.com/2007/11/16/rumorong-resident-evil-5-and-devil-may-cry-4-demos-on-re-extin/
LEFT4DEAD411.COM
Bet with disolitude: Left4Dead will have a higher Metacritic rating than Project Origin, 3 months after the second game's release. (hasn't been 3 months but it looks like I won :-p )