Is your PC or laptop laptop lagging behind in playing HD videos?Even if you have a good processor,graphic card and memory,it will not run HD videos smoothly.You need to have good codecs installed.Codec is what really matters.You need to have a good programmed codec pack.Use Combined Community Codec Pack.Its free.It delivers smooth HD videos.It comes bundled with many players.

Before installing,uninstall all other codec packs(k-lite codec pack).You may use the insurgent utility to find which codecs are installed