a few things i have learnt
3ccd (over in euro at least) is farking expensive
the single best thing to buy is a tripod
helmet mounted cams sound good in theory, but in practice, about 5% of what you record will be of any use
the best camera in the world won't mean squat, if you cannot process it (ie up load it to a PC with adequate storage space to download a high quality file type and then edit it)
and then the final product has to be burnt to a medium such as DVD, that again needs to have adequate capacity, to make your efforts viewable.
so look into the the size of the resulting files and their compatability to the movie making software you might have and the sort of final product you want to realise
of course if pixellated clips for youtube is your ambition... then meh, get the cheapest you can find!
Just coz you don't understand it
Doesn't mean it makes no sense!