Personally, I love these short videos full of hidden messages. After watching the video in hi-res a couple of times, here's a little theory I've come up with:
1: As far as I can hear, these terrorists are at some sort of airport.
2: When the terrorists are getting out of the elevator, right before they start the shooting, a sign saying "Security" can clearly be seen:

Maybe they're not just there to kill innocent people, but to take over the airport and, e.g, hijack a plane?
(Also note the four small images over the 2nd Security sign, one of them is the Stopping Power perk from CoD4...)
3: During the shootout, a number of images can be seen flashing over the screen. Look at this:

Clearly the inside of a plane. Maybe one the terrorists hijacked from the airport?
4: And finally, compare the image above, with this one, from the Mile High Club mission from CoD4:

Quite similar, eh? Also, the terrorists from both the airport and Mile High Club were russians. It is possible IW developed a storyline based on the ending of the previous game, and that one of the first missions in MW2 is similar/the same as Mile High Club, maybe like the cargoship from CoD4.
In addition, right before the terrorists are getting out of the elevator, one of them says either "Remember, no Russian" OR "Remember,
THE russian". The VIP from the plane in Mile High Club was russian.
I don't know, maybe I'm really good at seeing connections where there's really nothing. At least it makes perfect sense to
me.