Necromis,
what the video comes down two is three major tips and tricks...
1: Sneaking and blades:
sometimes you want to clear out a room, pick of targets one by one so that you are not outnumbered 5 to one. What you do is, sneak as far as possible and attack. If however you are spotted by an enemy you will want to 'lure' him out, stay in sneak mode, pull back till the last known safe zone and kill him there, he will be chasing you, yes, but other enemies won't. you can use this technique over and over again till all enemies are taken care off.
2 sneaking and archery:
Archery and sneaking is very handy for picking off enemies one by one and remaining at a safe distance. What you need is two 'area's'.... One attack position and one hiding spot. You will want both of these to be around 10meters/15yards away from each other.
Sneak into your attack zone, fire an arrow and 'escape' to your hiding spot (stay in sneak and don't move). The AI wil generally go straight to your attack zone, and will not look any further in the room.
Wait until enemies return to their posts and move into attackzone again and fire another arrow (or two if you are fast enough). DO NOT FIRE FROM THE SAFE ZONE AS THIS WILL COMPROMISE THE SAFE ZONE!!!!
3 Aggressive Pulling/sneak Archery.
To pull of an aggressive sneak archery shot, you must wait till the guards return to their spots and fire, return to safe zone, till wil search '10 seconds', return and then you move ahead 10mtrs take a few shots and QUICKLY move back into your safe zone.