In the following clip, a climber demonstrates two things. First, he shows us how to tie a munter hitch on a carabiner clipped to a harness. And second, he shows us how to mule off a munter hitch that is clipped to a locker on a pre-equalized anchor.
The munter-mule is one of the most useful combination's that one can employ in any rock rescue scenario. It provides the basis for load transfers and for a number of other rescue techniques.
In the video, the climber refers to the mule knot as a slip knot...which it is, but the official name for what he is doing is the "mule."
It is important to watch how the climber releases the mule. He never takes his hand off the break strand. I believe that the most common mistake that people make in this particular setting is that they completely let go of the break strand as they jump their break hand up the strand and closer to the hitch. When you practice, be aware of this and be careful to avoid letting go of the break strand.
--Jason D. Martin