I gave up after a few weeks as I had such a faff getting the camera attached to my helmet and facing the right way. The headband didn't work as the helmet comes down too low on my head; I bought a doo-dah from dogcamsport which consisted of a rubber block and some alternate-sided-velcro strap, but I can't work out how to attach it and even when I do, the camera still isn't pointing ahead - so that was abandoned too. (I've emailed them for help, but they had no instructions and said they could talk me through it on the phone, but I'm one of those people who needs visuals to do something like that).
In the end I bodged it using rubber bands so the camera was poking out through a front vent from the inside of the helmet, almost like a Dalek's eye-stalk. But faffing about trying to get the recorder inside my rucksack without it moving and disconnecting the leads / switching itself off was the final straw. It came off and has never been used again.
Bear in mind though that this is one user's experiences - Magnatom has no bother with his and can get it attached and working in minutes (as I witnessed first-hand in September). You may have no bother at all. I guess it depends on:
(a) your head shape
(

your helmet
(c) the type of camera and/or recorder you get
I'll be giving mine another go once I'm commuting in daylight again (Archos 605 WiFi + Archos Gen5 Helmet camera). One day I might get it right !