Hi nihner,
I'm a 27yo, moderate fitness level but predominantly running background with no real strength work. I got the force kit and am currently six weeks in and loving it. The first two weeks were tough just to get used to it but now I have the hang of it. As was mentioned, the best thing about the TRX is that you can adjust the difficulty as you progress and also increase the intensity by slightly modifying the sets.
As such I would think you could physically do this, just maybe not at the same difficulty or intensity that is first demonstrated on the DVD. Also if you do get it, remember the DVD is a sample of the workout at week five so your workouts and sets will be easier than demonstrated.
Also think as to what you want to get out of your workouts. I find the Force training schedule is very much focused on functional strength; lifting, hiking, leg strength, core and back strength. They even say as much on the DVD that it focuses on back strength and not really aimed at developing a big chest on that program (done to accomodate hiking with a loaded pack, etc which would otherwise cause back injury). That said, the TRX website has plenty of other exercises that you can incorporate into your own workouts.
Hope that the info is some help
James