XViD

Xvid Codec Links - Video Codecs - Win, Mac and Linux

Codec is short for Compressor-Decompressor. Codecs are required to encode and/or decode (play) audio and video. It would be wise to un-install any existing codecs before installing a codec pack.

Your best bet is to go to Codecguide.com and get the K-Lite Codec Pack or the Mega version which includes the K-Lite Codec Pack Full, QuickTime Alternative, Real Alternative and BSplayer. All the codecs you will ever need (including realmedia and quicktime files). Use the included "Media Player Classic", it beats the heck out of the big guys players, it does not phone home everything you do and is fully opensource.

The K-Lite Codec Pack is a collection of codecs and related tools. It is designed as a user-friendly solution for playing all your movie files. With it you should be able to play 99% of all the content you happen upon (DivX, XviD, FLV, AC3, WMV, WMA, MP3, MPEG1,2&4 etc..)

For a wide selection of codecs and programs related to multi-media see Free-Codecs.com

Comparison of video codecs - Wikipedia
Comparison of media players - Wikipedia
Media Player Classic - Wikipedia Included with K-lite Codec pack
VLC media player - Wikipedia
VLC media player The cross-platform media player and streaming server - Windows, Mac, Linux and Unix
Google Video - Wikipedia
Flash Video .FLV files - Wikipedia


Note: Codec packs and filesharing clients are completely free. Ignore the fraudulent scam sites that ask money for them. Codec packs and filesharing clients also do not require subscriptions of any kind: these subscriptions do not exist. If you have been tricked into paying, then contact your credit card company to see if the money can be refunded.
Free Video sites:
Google
YouTube
Replay guide - Thousands of Stations and Shows
Apple movie trailers
IMDB trailers