I gathered the available GTA IV trailers for myself and others who may like to rewatch them for fun and or nostalgia :)

[video=6168304]

http://www.gamespot.com/grand-theft-auto-iv/videos/grand-theft-auto-iv-official-trailer-1-6168304

[video=6173289]

http://www.gamespot.com/grand-theft-auto-iv/videos/grand-theft-auto-iv-official-trailer-2-6173289

The third one is just a painting of the game's cover

[video=6183745]

http://www.gamespot.com/grand-theft-auto-iv/videos/grand-theft-auto-iv-official-trailer-4-6183745

[video=6189948]

http://www.gamespot.com/grand-theft-auto-iv/videos/grand-theft-auto-iv-official-trailer-5-6189948

[video=6188467]

http://www.gamespot.com/grand-theft-auto-iv/videos/grand-theft-auto-iv-good-lord-what-are-you-doing-6188467