I just want to make sure folks understand the problem here as it took me a moment to see it:
You can actually count the number of shorter-length bricks between the two vertical lines under the window (or piping) in either photo. At all levels, there are only nine (9) in the alleged 'gassing' footage site, and there are ten (10) under the window at the Mogilev institute photo.
There is also a ledge which protrudes underneath the window, whereas there is only some questionable protrusion under the 'chamber' piping, and in any case the bricks which are on the questionable 'chamber' ledge are shorter (half-length) compared to those on the obvious protruding ledge under the window of the institute (full-length).
Compare this:
To this:
I think the biggest discrepancy remains the fewer number of bricks (nine vs. ten short bricks) between the "two [vertical] lines", especially since these two "straight lines" are reportedly (per Sergey) stated by witnesses, making this an important feature to consider.
It is still possible this is the same building and that Sergey just identified the wrong window but then, if so, we still face the lack of an original film/source, questionable provenance, inconsistent and/or dubious testimony, and typical pattern alignment with other Soviet post-war hoaxes and deception.