KMPlayer lacks a help file but makes up for it by being one of the most powerful freeware video players we've seen. It includes a vast array of video- and audio-capturing options, as well as skins, a plethora of playback controls and tweaks, and broad DVD support. You'll have to learn the ropes yourself, but if you're familiar with where things ought to be, and willing to patiently wait for the mouse-over label to confirm your suppositions, KMPlayer has the potential to be immensely rewarding.
It supports nearly every file format we could think of testing. It did have problems with RealPlayer 11's video capture IVR format, but not much else. Throw in the advanced features such as frame capture and a frame-forward feature, the ability to stream TV and HDTV, playlists, and the ability to choose codecs on a video-by-video basis, and you get a media player that demands attention.