It's a mod that changes the game elements to provide more true "widescreen" for players playing with widescreen monitors that are better suited for 16:9 aspect ratio screen resolutions.
In an attempt to bring these changes it also modifies the players FoV (Field of View) this is what makes it a problem in vcmp. Because of the changed FoV it makes players shots that are perfectly on target at the enemy from weapons such as M4 miss you on your screen.
To be more exact it moves the players shots on your screen (If you have widescreen fix installed) over to the side about half a metre. I believe it also has the same effect for the player using widescreen fix too. i. e you shoot at a player and you hit them on your screen but on their screen it they see you shooting to the side of their character too.
Basically it happens because 2 players are playing at different field of views which causes the weapon sync
to become messed up. If 2 players were both playing with widescreen mod they could hit each other fine.
So to sum up:
No widescreen fix vs No widescreen fix = hit
Widescreen fix vs No widescreen fix = miss
Widescreen fix vs Widescreen fix = hit
