Tonnes of Left 4 Dead 2 footage here, the main one showing off the new nade launcher. Can't honestly see it's purpose in-game but who cares; it's a nade launcher. Maybe it'll be useful for clearing crowds of infected from an incapped survivor, or maybe it'll be used to cut down a charging tank. Who knows? Whatever the case, it'll mainly be used to grief people.
This video shows off the new improved AI fire mechanics. Great stuff!
Here is another new gun - not an AK47, but close to it. Gorgeous graphics as well.
This is a nice, slow paced video. Gives you a chance to admire the details.
This is my favourite video; it looks gorgeous fullscreen.