+++++++++++++++
AND THE FINDINGS>>>
It is indeed just a shadow on the wall. I downloaded the video, expanded the area, set it to high quality, and here is how that looked
there is a angled wall at the beginning, the shadow emerges from the corner, and seems to be elongated, as if someone is passing close to a
lightsource, the shadow then moves across more, it squishes up at the corner..you see the shadow reflected from the wall down the hall, giving it the
appearance of "legs", when in reality its just the highly polished floor reflecting the shadow..the shadow gets thinner the more it goes (which
happens when your walking away from a light source).
So, my theory is that this is just a shadow of someone in the other room (the most convincing part being of course where the shadow seems to merge
with the overhead lamp shadow..
I slapped this together real quick to demonstrate