James Mason :
uhh, why the f would you want to use a 4:3 ratio on your computer and monitor?
And uhh, do you have an example where he run's 4:3? All his youtube videos look to be 1080p.
My guess is he's having trouble achieving 300+FPS and wants to drop his resolution so he can get that. Apparently the game's tick rate is tied to the framerate, and you can't be competitive without some ludicrously high framerate, so all the pro players run the game at 1024x768 with all the graphics settings turned as low as they will go.
The problem with running that low a resolution, is it just isn't going to look good on an LCD display with a much higher native resolution. Now if you're watching gameplay footage from somebody on Youtube, or on a Stream, you're likely getting it from a capture card or recording software, and not seeing the footage on the monitor itself, and that's why it looks better.
As for your problem, I take it the image is stretching from 4:3 to fill your entire screen, and that's causing trouble. Try pressing the menu button on your monitor, and look in your options for something that might be set to stretch the image to fit the full display, and change that setting so that it doesn't. On Samsung monitors it's image size and the options are wide, which stretches it, and auto which will use the aspect ratio of your selected resolution, I don't know how BenQ does it, so you'll have to try to find it.
If that doesn't work, then you may just have to put up with the blurriness or get a much lower resolution display to play CounterStrike on if you insist on running at such a low resolution.