We heard a slam from the opposing hallway and upon reviewing our DVR footage, we noticed the window opening. We investigated the said window and then setup some equipment to see if we could capture it again. We never heard another slam for the rest of the investigation. But, after reviewing all our DVR footage, we noticed that the occurrence we thought we caught only once, had actually happened again. Here is the footage of both occurrences. 

We sent the video to be reviewed by specialists in wind tunnel effects/stack effects. A location layout was sent along with the footage and weather conditions were taken into consideration. Its official, they believe that it is NOT caused by any type of wind effect, stack effect or negative and positive air pressures and labeled it as a strange occurrence.