Despite lacking a Help file, KMPlayer is 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, perhaps a hindrance to newcomers. But if you're familiar with where things ought to be in programs, and willing to patiently wait for mouse-over labels to pop up and then click on them for the actual menus, KMPlayer has the potential to be immensely rewarding. It supports all major file formats, and all of the minor and obscure ones we tested. It did have problems with the RealPlayer 11's video capture IVR format, but not much else.
Advanced options include frame capture and a frame-forward feature, which is actually a fractional Play button, but the difference is negligible. The Pause button is a fast responder, too. Combined with streaming TV and HDTV compatibility, playlists, and the ability to select which codec is used on a video-by-video basis, and you get a media player that demands attention.