The whole interview is simply a test to see how well you handle yourself in a new situation, and how well you interact with complete strangers. Do your best to RELAX prior to entering the building. Have a nice cup of tea, listen to calming music, face yourself in a mirror and psych yourself up, tell yourself that you are going to get the offer!
The interview process was the same as most have mentioned, group activity, video presentation, Q&A, group interview. Most important thing to remember is that you are being watched by the recruiters the ENTIRE time. Smile, smile, smile, show those pearly whites. You are sitting next to someone? Strike up a conversation (where are you from? what do you do? anything!). Make excellent eye contact, when the presentation is happening, make sure you watch of course, but also make eye contact with the presenter, make sure they know you are actively listening.
The recruiters will tell everyone "please try to relax and just be yourself", this is so true. I saw many people who were not offered the position who in my own beliefs were too rigid. During the group interview, you'll be asked a question. Yes, we know you've practiced and practiced and practiced your response to "why do you want to work for American", but when it comes to actually answering in person, don't just rant on your prepared monologue. The recruiters are looking for originality and character, be professional but be casual. Answer the question like you're having a conversation with a friend or family member, not like a robot.
Another thing to note: the process following the group interview and video presentation, was different for everyone. Some people went straight to a room for their individual interview, some were instead taken to do fingerprints, and some were taken to do drug testing (and some sadly were taken back to the airport). They mixed it up with everyone, don't be a nervous wreck if you leave the video presentation and are taken to do fingerprints before the individual interview .
They offered me the position on the spot, but I know of many people with AA and other airlines, where they didn't get a CJO for a few days later. Just relax and if it happens it happens.
VERY IMPORTANT! They may or may not drug test you on the spot. Be prepared for this.