In reply to alps_p:
I use the basic head strap (with the rubber grip) as my helmet is smooth. I once used the sticker grips but when climbing in the ice and cold the glue stiffens up and it easily falls off with the slightest bump.
Also be aware, last climbing trip i managed to scratch the lens becasue when it is on your head you cant see where it is in relationship to the wall......£12 spares are available on the net. I think i am going to get the chest harness as there will be less liklihood of knocking it and the videos will be smoother. Sony Vegas Pro has a "stabalise" option if it does get a little bouncy.
Hope this helps
Mike