I sure hope that you'r3e planning on practicing the 'Mjolnir Mix' and play it on hard or expert in the video.
Here another hint. Set up seperate shots of you in the suit , then the guitar and then the game... don't just wobbly pan to show each thing. Doing that makes it look like a home video your kid brother filmed or something... Use a tripod, set up specific shots... Also if you're going to use GH3 footage, maybe consider having video of the full song captured with a capture card, then editing in clips of play... shooting the TV with your camcorder is another quality issue..
Good luck with this Sigma... don't hesitate to show us your progress from time to time.