The preview also talks about how the passage of time might affect the game, and the trailer indicates this in subtle ways.
The idea was to show a real street-level view of Rockstar's version of the city with a band that belongs there. To that effect, you'll be seeing even more licensed music from all genres and time periods, since the soundtrack team is no longer confined to a specific decade.
We'll find out more about this when the trailer is released at 12:00 EDT today, that's 5PM in the UK.
UPDATE: I would imagine for many of you this is the first time you've heard of this band. They appear to be an Indie / Experimental band and you can hear a few of their songs on their MySpace and Virb profiles. Both have the song "Arm In Arm", albeit a different remix, but this is the sort of thing you can expect to hear in the trailer.