Ex-Royal Air Force helicopter force here, spent a lot of time around Chinooks.
I think the main answer is "because I can", but I can think of a legitimate combat use.
You are heavy, and forced to land downwind into a narrow strip because there is a hazard on the upwind side of the landing zone.
There is not enough room to turn around.
You could hover taxi backwards like this to pick up some inflow into the rotors from the relative airflow (and therefore increased lift), then climb away backwards until you do have enough room to transition into normal forward flight, more or less as shown in the video.
This is where team work kicks in - you've really got to trust your load master who is telling you exactly where you are.
Never seen it done though.
aviation.stackexchange.com/users/595/Simon
What you are seeing is whats called a Pinnacle Landing or Pinnacle Maneuver .
Why its practiced is much cleared from the below image.
The Chinook has a large base that may prevent it from safely landing in circumstance that require an evacuation from a small raised area.
aviation.stackexchange.com/users/None/
It looks like it's done to showcase the impressive level of skill & control that the pilot is able to achieve w/ this aircraft.
Sort of like the Ken Block Gymkhana video series, where he's showing off amazing car control, but you would never want to drive like that except in a drifting contest.
Stretching the definition of 'practical', if you needed to tow something a short way & you had no pickup truck available, but somehow you did have a Chinook helicopter w/
a world-class pilot....
this would kind of be an option Source: I just enjoyed the mental image of someone using a Chinook as a pickup truck
aviation.stackexchange.com/users/14424/Nathan Smith
When our CH- 46 (PHROG) pilots are moving the aircraft on the runway they were directed by ground crew like myself, there are plenty of times we would taxi them forward and backward
so I don't believe it would be "just because" or "showing off".
It's part of every pilots training as is the rear wheel landing or "pinnacle landing" which is used to land on rooftops and mountain tops hence pinnacle.
aviation.stackexchange.com/users/19788/Jay
My guess is that if you need to get into and out of a 'hot' strip this approach would minimise the time (and position in the sky) that you would be exposed to enemy fire.
Just the sort of flying that might be needed on special ops.
aviation.stackexchange.com/users/14445/Robert Loft
At 4:30 in this YouTube video, a Chinook traverses the runway on its rear wheels. The text on the video lists "Emergency landing and take-off". Is there any reason for the pilot to do this other than "because I can and it's an airshow"?     The pilot then proceeds to back down the runway on the rear wheels, a maneuver that I can only imagine is showing off, but again, is there a legitimate flying need to do this?
What would the reason be for this helicopter maneuver?
aviation.stackexchange.com
<landing><helicopter><ch-47>
aviation.stackexchange.com/questions/26826
aviation.stackexchange.com/users/5517/FreeMan
This maneuver is called a Pinnacle Landing. It could be used tominimise the time you would be exposed to enemy fire. It also showcases the impressive level of skill and control the pilot can achieve with this aircraft.  While some believe that this maneuver is being performed to showcase the pilot's skills, others state that it would be performed if an evacuation was required from a small raised area. Another possible reason for performing such a maneuver would be to reduce exposure to enemy fire in a hostile situation
This maneuver, known as a pinnacle maneuver, would be performed if an evacuation was required from a small raised area.  The maneuver is being performed to showcase the pilot's skills. This maneuver would reduce exposure to enemy fire in a hostile situation.