.mdf extension

I need to know where I may download a mdf codec, in order that I might view a video with this extension.

MDF is an Alcohol image file and you have a few options: burn it or open it, Alcohol 120% has a virtual drive for that or Daemon Tools. If you want to extract it you may use any iso tool like Isobuster,MagicIso WinIso UltraIso and so on.