The clips are introduced by Jim Cameron who describes to us the character of Jake, as well as the set-up and story of the film. He also mentions that all scenes are from the first half of the film, so there's no need to worry about major spoilers.
The clips start off with Col. Quaritch (Stephen Lang) briefing his troops about Pandora and the Na'vi. In the process giving them a bad name, by describing them as everything that they aren't. He also tells them that he can't promise he will be able to protect all of them and that they all may not survive, because they won't. Halfway through the briefing Jake rolls up into the scene.
The next clip is of Jake getting ready to connect with his Avatar. Dr. Grace Augustine (Sigourney Weaver) offers to help him into the pod, but he says he is fine. Its obvious that he is excited and eager by the whole process and possibility, as she tells him numerous times to relax, put his head down and blank his mind. We also see Augustine's team in the background getting ready to perform the procedure, one makes a comment that Jake has a good brain.
Augustine then informs her team to get ready to begin the process. It appears as though she is about to go through the same procedure as Jake, as far as I can recall she was walking towards a similar pod as the one Jake was in.
The next clip begins from Jake's point of view, all blurry and cloudy where he has now finally connected to his Avatar. The doctors and medical team around him check to see he is functional, respondent and has full control of his senses. They ask him to sit up and touch his thumbs with each of his fingers and to wiggle his toes.
Clearly the experience and feeling of being able to feel and use his legs again is all too much for Jake. The doctors tell him to remain seated, but he is too eager to stand up and walk. It all gets a bit hectic with the team and doctors behind the screen asking him to remain where he is, and preparing to sedate him.
Jake continues though, stumbling as he gets up onto his feet and tells them he is alright. Another person (I'm assuming the guy behind Jake when he is looking at his Avatar in its test tube) who has also gone though the same procedure tries to calm Jake down and get him to listen to the doctors. We then see the shot from the trailer with Jake saying, "It feels great".
The other guy then asks the team to get all the equipment and wires off of him so that he can go and calm Jake down. The scene ends with Jake going through the door of the room they are in.
The next clip begins and we are now on Pandora, where Jake, Augustine and the rest of the team are face to face with a Hammerhead Elephant I believe. Augustine tells Jake to remain calm and to slowly move away. The hammerhead charges at the team, and at the same time Jake charges at it shouting. The hammerhead stops about a foot away from Jake, turns away and runs. Jake thinking it was running from him makes the most of the moment.
The beast we see chasing Jake in the trailer then appears from the surroundings behind Jake and gives out a roar. Jake then ask Augustine, "What about his one?", she replies, "Run! Definately Run!".
A chase then proceeds between Jake and the beast. Jake dives for cover at the bottom of a tree within its roots (It seems that mountain aren't the only things that are elevated on Pandora). The beast continues to try and grab Jake. Jake escapes out the other side and continues running with the beast in pursuit. The clip then ends with the beast jumping on Jake like in the trailer, though it goes as far as landing and grabbing Jake in the process.
The next clip is at night in Pandora and Jake is being attacked by dogs. Neytiri appears and takes out the hounds and saves Jake. Jake goes to thank Neytiri, but she hits him away, she also puts out a fire that Jake has going, much to his reluctance. One of the dogs is still alive and clearly suffering from his wounds from an arrow Neytiri shot at it, she goes over to it and mercifully puts it down, at the same time saying something in in Na'vi.
Neytiri then goes off, Jake chases after her to speak to her. She calls him pathetic and irresponsible saying he is like a child and that those dogs did not have to die. Jake then asks her, well why did you save me then. There is a slight pause before Neytiri responds to him saying he has a strong heart.
The final clip is off Jake along with Neytiri and more of the Na'vi on a mountain surrounded by the flying creatures that are seen in the trailer. They seem to be searching amongst them for the one that is compatible with Jake to bond with. Jake asks how will I know which is the right one. Neytiri replies that it will be the one that tries to kill you. One of the Na'vi jokingly makes a comment that, "That moron's going to get himself killed".
Jake walks amongst them and while some hiss and scowl at him, he replies in the same manner and they just step off or fly away. He eventually comes up to one who doesn't reply in the same manner and a struggle ensues between the two. Jake manages to wrestle control of the creature while tying its beak. Neytiri then tells him to bond with it. He does this by merging his hair with one of its attenaes seemingly.
Jake then gets full control of the creature seemingly though a mind link. Neytiri then hurrys Jake and tells him that the first flight needs to be made immediately. Jake dives off the mountain top with the creature and at first is unable to get it to respond. He eventually does so and the two take flight.
We then get a closing montageof clips, which is basically the latter part of the teaser trailer with a few shots replaced with new ones. I can' really remember any of these apart from one with Neytiri in a stance preparing to fight with someone or something.