Koyote Soft's Free FLV Player does exactly what its name suggests; supports playback of flash video content on a PC. Flash video is the format used with the world's most popular video sites such as YouTube, Metacafe, Google Video, Yahoo! Video and Megavideo, meaning that the amount of FLV files a user might might has grown significantly in the past few years.
The player also supports MP4 files containing H.264 video, HD FLV files, MOV and AVI files. You do not need to install any additional codecs of even Flash runtimes. It supports seeking and full-screen viewing.