Hi Emily,
The presentation is pretty much what you make of it in my experience. The "feel" of your interview is reflective of a lot of things: your presenters' personalities, your team's initiatives, your essay, etc. I find that if your presentation isn't a good fit for your team, it comes off as unnatural and forced. Stuff like props and a slideshow are not mandatory for your Chairman's submission, but they can be helpful. Note that there's not one "correct" way to do this. 2014's winners (27 RUSH) used a very polished looking video cart with videos and everything, while last year's Hall of Fame winners (597 Wolverines) used a potted tree in their presentation. I feel these two teams are a good example of two different presentation styles. Check out the winners page
here to see examples of past essays, presentations, and videos; it includes all of last year's Regional/District Championship winners and all HoF winners.
The video is actually not judged formally, but it shouldn't be overlooked. You should check the Administrative Manual (section 6) for the verbatim guidelines, but basically your video will not be viewed by the judges before they decide the award winner(s). If you're a top contender at your event the Judge Advisor will look over your video to make sure it's alright to show (no profanity, no copyright issues) but the actual Judges who decide the winner will not see it. It's basically a way for you to quickly sum up your team's efforts to other teams. It's an opportunity for you to have fun in a low-risk medium. Tip: audio quality is more important than video quality. Prioritize a microphone of some sort over a good video camera.
As a final note,
Team 2486 has some fantastic resources on their website about the award. You should check that out to get another perspective on the Chairman's Award. Good luck this season!