This is a port of awesome glow retexture to simiulate Anomorphic lens flares. I think it looks even better in L4D2 than in Counter Strike: Source. Enjoy!
EDIT: BF3 Edition: http://www.gamebanana.com/l4d2/sprites/3692
Please redownload it, should look WAY much better now. And remember to have only one version at a time, delete old version and put new one (BF3 edition or normal).