The AvPR presentation at the LA Comic Convention was a couple of hours ago and we have the first report of the footage shown thanks to forum member El Diablo:
“The footage begins with the Predator walking through the hallways of a hospital, which has now been turned into an alien hive. the predalien dropped down from the ceiling behind him, smacks the predator with his tail, and sends him crashing through a wall. An alien warrior drops down in front of the predalien, almost protecting it, and attacks the predator. the predator shoots it with a handheld plasma caster. a second alien attacks, the predator drops it to the ground, shoves a glowing blue vial into its mouth, causing it to melt from the inside out.
this blue vial as later explained by the straus brothers”, is actually a chemical that the predator uses to get rid of the evidence of the alien bodies while on his mission. there are two more alien warriors that are climbing the walls of the hive towards the predator. he throws two shurikens. it kills both aliens, but one shuriken continues flying, that’s the scene from the trailer where the female character, who is running past the hallway with the rest of the humans, is pinned to the wall. (her death was an accident).”
Keep checking that thread as it may be updated with some new stuff. The directors mentioned something about AvP3 in the Q&A session.