Yup that's how you take a tree down using another tree to rope down/ lower the tree your removing.
However the tree they're using to lower the stem of the tree they're cutting down is a little wimpy for those size pieces. 
I'd be taking smaller sized pieces of the stem of the cut tree or they're going to snap the lowering tree and create a real mess. 
As an example.
The closest call I ever had to getting seriously injured or killed doing tree work was:
I was on the ground in a cramped fenced in pool area.
I was between a tall wood fence, an old aluminum Sears shed and the lowering oak tree with only 1 exit.
I was "on the rope" on the ground doing the lowering of some huge oak lumber from the tree being cut.
We were using another huge oak tree next to the tree being cut as the lowering tree right next to me.
The rope runs from me holding it > up and over a very sturdy crotch of the 'lowering tree' > the climber up in the 'cutting tree' ties off the piece being cut > in a very controlled manner I let it drop & swing below the climber until it stops swinging wildly.
I have the rope wrapped around the lowering trees lower trunk several times > the friction of the wraps acts like a brake and let's me lower lumber/branches with one hand many times my weight.
Now here's where the freak accident happens > the very sturdy crotch of the Oak lowering tree (unknown to us) is completely rotten inside from ants and termites (total swiss cheese) > it held up well for most of the lowering until we got to the big lumber from the stem of the cutting tree > with about 40' left of telephone pole stem of the cutting tree the climber was "chunking" down huge logs >
That's when the swiss cheese of the lowering trees crotch had had enough > big log .. 3' across 4' long 40' up came crashing down on the 1st swing along with the whole oak limb that was the sturdy crotch.
I was hemmed in by the fence and shed with no where to go > drop to the ground, make like a hole in it > the whole kit and caboodle waffled the shed, the fence and the edge of the pool.

My fellow ground comrades came a running to dig me out of the whole mess of rope, log and "branch" .. think small oak tree.
I emerged under my own power with some minor scratches, but shaking like a leaf, no pun intended.
The boss, my dear friend Captain Kirk let me go home early that day to get some clean skivvies and pants.
