The guard dies at 45:56.
The player presses quicksave at 46:06.
We see the guard is still dead at 46:16.
Then he presses quickload at 46:22.
And we see the guard is alive again at 46:32.
Indeed, the guard should be dead.
I don't know why is this.
I did a quick test, although not with the level in the video.
For me, dead guard stays dead.
Maybe I try it with the level in the video as well...
(Micro Palace, level 11)
UPDATE: I tried it on that level. I even pressed quicksave where we see it in the video.
The guard stays dead for me after quickload.
EDIT: Attached the quicksave file.