Well, in my post I stated the time of world record run in the section. (Which is ~18.76) With only 20 minutes of practice that day, I got the time of ~19.3-19.5 seconds on the section. That day I said we could match or even surpass the world record with this strat if there is enough practice. (Unlikely to surpass, but highly likely to match) Right now I am getting an average of ~19.0-19.1 and my fastest was ~18.74. There is a chance that this method would be FASTER than shooting the camera and the guard. I hope this clears some things up.

Sorry for the Quality, Using Roblox's Recording Software.

If you crouch and wait for the guard to come and shoot just when he finds you, and you grab the keycard while crouching and do the normal stuff after - it is easier and may have a chance to be faster. Right now, I got it down till around ~19.3 - 19.5 seconds on average for the Section (Spawn until opening the door with the keycard), and I have only been practicing for ~20 minutes. Right Now, the world record is like ~18.76 on that section. I think with a bit of practice, it can be done. (What I mean is instead of shooting the camera and guard, why not only shoot the guard?) This is a video to show an example of the Strat: