VideoSpec - VideoSpec is a free AppleScript studio App (Xcode 3.
Moo0 Video Info - Moo0 Video Info is a very easy tool which can dispaly each video / audio file's information.
GSpot - GSpot is a Windows-based freeware designed to identify codecs used in video files.
MediaInfoXP - GUI for MediaInfo, an open source tool for displaying technical information about media files.
Avicodec - AVIcodec is a free multimedia file analyser for Windows.
CodecInstaller - Ever had a movie where you could only hear the sound and there were no video?