No sermon, Lee, and with no real working knowledge of your components, though I am familiar with iMovie and Final Cut Pro but not Final Cut Express, I'd say what you want to do isn't at all impossible. The latest MacBook Pro systems have Intel Core i5 or i7 processors and NVIDIA graphics for games and video quality. They come with 2 USB 2.0 ports and one FireWire 800 port.
So, if you have something like that you should have the connectivity needed for inputing or digitizing video live. It will depend on your storage (don't use your system drive, especially if it's a 5400 rpm for recording video) and the speed of your external hard drive(s) and capacity of course. For what you want to do a MacBook Pro doesn't wind up being all THAT portable, what with external components and hardware and stuff like a large capacity external FireWire hard drive for recording video from your camera.
Your flash recording medium based camera is a good quality HD unit but reviews note that many models in this arena have "fairly useless" manual focus. It's a CMOS 1/3.2 size sensor recording to AVCHD. And it has USB 2.0 compatibility, but apparently not FireWire - 400 or 800. The lCD display may come in handy but keep in mind that you WILL be tethered to your MacBook so don't get carried away to the point you overlook that you're dragging your computer around at the end of those cables. I could not confirm or affirm if your unit has audio in/out, if not that is certainly going to be an "issue" with music video production.
Evidently there must be SOME kind of audio ability anyway because you have those two AKG CS1000 microphones. And I'm not at ALL familiar with Digidesign's Mbox 2 audio interface. Only to read that what you have is a $400 plus piece of hardware there. And USB-powered! That's another piece of equipment, however, that you'll be dragging around tethered to your camera and laptop.
So, Apple says FCE has "built-in AVCHD" so your camera and editing software seem to be a match as well as the Mbox and AKG mics - all presumably "happy" with your system.
Bottom line, seems you simply need to figure out how to be mobile enough to get the shots you want with your camera, without ripping loose your various connections. Oh, and you'll probably need SOME auxiliary lighting, though most MUSIC VIDEO venues aren't going to be pleased with that, what with all the dark and flashing light show they already want to put on.
Your equipment is relatively stellar, so rigging up some way to be "portable" with all your gadgetry, piping in the shots and audio you want, "fixing" everything in post with FCE, then you should be able to pump the end results to your YouTube account.
Of course this all assumes you DO know how to frame your shots, get cutaways and B-roll footage, handle various audio issues and have some concept of color control, white balancing, etc. Hope this helps.
Earl