For the shoot I did today here in Doha its a full harness that you put your legs through and then a strap across the chest.
I used an AW139 as a camera ship today so used the anchoring straps around the bottom seat rails. I tightened the tether so I am at the door edge but no further. Once its anchored in I ALWAYS grab the end of and put all my weight on it to ensure no movement. Then hook up and away we go.
Me personally I dont lean all the way out hanging on the harness, dont see the point, wouldn't put the pilot in the position of filling out all that paperwork if something let go. Besides there is always a way to get that unique shot you want without being all the way outside the helo. For example today I just sat on the floor of the 139 in the doorway and shot for 2.3 hours and got everything I needed.
For those that are interested we were shooting Gulf Helicopters new AW189 as well as the S92
Just my two cents worth.
Ned