Rasher, if you are not going to do much filming and already have a camcorder, either mount it that so that it can film as you go along* or (if it has a suitable input and controls) buy a bullet lens and a LANC switch. Stuff the camcorder away somewhere and control it off the switch.
The trouble with tape is that it renders itself onto a PC for conversion and subsequent editing (vital if you are not to bore the pants off yourself or those viewing) in real time.... ie. bloody slowly. A card or hard drive device creates a simple file, just drag it across... then do the conversion (if necessary) and start your editing fun. If you just want to show your mother-in-law your jaunt on the TV, your basic camcorder will be fine, via it's line out socket... just make sure you stop the show before your home made alpine porno shoot starts!!!
I have used a waterproof Sony digital camera with some success, too. In fact, if it's not going to rain just about any modern point and squirt cheapish digital camera will have a basic but reasonable enough stab at the job. Just make sure you can operate the on / off button with gloves on. Or, stop, start the camera, ride, stop the bike and kill the camera, which is not too onerous a task either..... edit out the bits later. Or just play it back through the TV, if that's all you want to do.
*A Ram mount / one of those larger sticky sucker mount things will do. It may be a good idea to attach a safety cord to the camera, just in case it decides to make a bid for freedom
Toad of this parish has a Ram mount on a longish flexible arm, which he mounts on the rear frame of his GSA. The advantage of this set-up is that you can swing the camera around or change the camera's position and angle quite easily. It doesn't seem to get in the way of anything nor suffer from undue vibration or flexing. I think I may get one.
All in all, a purpose made digital mini camera (like a GoPro or Drift) are probably best overall. One with a simple remote control (the Drift for instance) is an advantage. One with a view screen helps set up, too. Again the Drift has that, along with a rotatable lens which is helpful if the mounting position is not 100%. Toad (he again) had a neat camera with a very simple twin laser (a bit like a cheap measuring / level device) to help set up the camera square on.
If you buy one, it's a racing cert that you can sell it on later.... so have a look in the FSW section or on any auction website, you'll find something.
PS What the hell any of this thread had to do with 1200 GS motorcycles is a mystery. But hey-ho it makes a change from, 'What gloves will fit my feet?'