I was the special emphsis pt instructor (PT for MEDDAC Soldiers who did not meet standard) for 2 years at my last duty station and I incorporated P90X constantly in my PT regimine. I even once gave PT to the whole hospital in preperation for a PT test and took them through the ab ripper, it was well recieved.
I tried insanity when I got to my current location cause I'm attached remotely and have to do PT on my own. I did it consitantly for about 2 weeks and then had to back off because of all the plyometrics got my knee all inflammed. I enjoyed it but way to much jumping and I was conditioned before I started... If you want to start a PT routine Insanity is not the way to start but is something that you can pick up after you have had some good conditioning. P90X is good right off the bat. Either way though you need crazy amounts of personal motivation to stick to any at home program.
It's easy to blow off home routines, finding a local gig and meeting up with people is a lot better in my opinion because you have a support system to keep you motivated. Just my opinion.