for me theres several options for cameras
either still video or both (either or) some cameras cando creditable still and video images
within that choice ones with or without remote controls
consider one which can be powered from the bike... not another set of effing batteries
you need to think what you are going to do with the images.. if they are for your consumption on your own PC or on a local network or if they are to be shared eg on Youtube or similar. if 'all' you want to do is post stuff on youtube then bear in mind hi res video consumes around 40mb of space a minute. thats a heck of a lot of data to pump and down the connection.
some of the free easily available editing software can't handle big files.
having said that theres a range of cameras out there. I think Gustavo has just bought an EBAY special paid $10.01 shipped from Hong Kong.... it isn't going to rival Spielberg / Cameron but assuming its the same as has recently become popular on the versys.co.uk site the image quality is fine. or you can pay upwards of $600 for a picture in picture dual camera D1 DVD quality setup, which is used for some of the motor racing coverage used by broadcasters
the fancier kits come with lots of adapters and fittings, including suction cups, clamps and so on. the simpler ones do not.
the camera used for that is a bullet /lipstick camera, mounted on the tank using suction cups (3) connected to a HDVR recorder with remote control. one problem I have found so far is keeping the lens clean from crud thrown from the road from other users.
I find the helmet mounted style to off putting as I tend to move my head constantly scanning for hazards or enjoying the scenery and not looking for hazards
. the video results make me feel travel sick
before spending cash decide what you want, decide who realisitically is going to be interested in your bike videos/photos..... most people will tire after the first 15..30 seconds tbh.