Very impractical for airsoft, at least out beyond a 100 or so feet, weapon dependent. Also, I came into this thread waiting to see the coolest sniper rifle, so where is it? All I see is an AR with nearly zero tactical application. Could you imagine trying to use this style of target acquisition on multiple enemy hostiles moving in? It would be like "lock on damn it! Shit he moved! Fuck, he's behind cover again! Hey! They're getting closer! The guns only let me take three shots so far and two of them missed! Also, I think the first one only winged buddy in the arm! Okay, I'm taking this stupid thing off my gun! Wait, it's integrated, you mean I'm stuck with it?! Well, I guess I'm switching to a pistol then!" ...Or something.
There's waaaay to much speculation on what the coolest or most badass sniper rifle is, so I won't bother. Technically you could say whichever owns the longest shot, can cause the most damage, or perhaps has the most consistent kill volume could fairly take top spot. Rifles like the Cheytac, Arctic Warfare, etc, would definately be near the top of the list.
Here's a much more valid video about an "in testing" .50 caliber sniper rifle round.
There's a few other videos out there on this.