This climbing video is also on youtube in HD!
Graeme descends onto a dead and rotten tree so that he can safely work on it. After lopping out the head, the rest of the tree is blocked down.
When the tree we are removing is too dangerous to climb or be attached to normally, tree loppers will often gain access from another high point. This particular Mountain Ash was over the top of a high visitation walking track, and was one of several dead Eucalyptus regnans that needed to be removed for public safety.