That technique is known as a "toe-in" - though I had never seen it performed with a Chinook - and its use is very common with putting down and picking field crews in Alaska and western Canada. Be gentle when you're tossing your pack into the ship...
Well actually, the pilot is backing in to the mountain, so I suppose it might technically be called a "butt in"?

What is especially interesting in this case is that the pilot is facing the other way, and therefore he/she must be very dependent instructions from a crew member at the rear of the ship to get the aircraft into position while keeping the rotor clear of the mountain. One advantage of backing in with the Chinook is that the tail rotor is higher than the front rotor, which gives some extra clearance.
"Toe ins" and other variations such as a "one skid" are indeed used from time to time to put field crews into spots in rugged terrain. And yes, one climbs in/out of the ship very gently, especially with smaller, less powerful helicopters!