If you wish to playback most existing DivX movies well, you may want to download the 3.11 Alpha version of the Divx codec instead, as other versions may not be 100% compatible. If you want a completely "legal" codec that has built in 2-pass encoding, you should try the DivX 4.x codec (the codec on this page), which is the latest version of the DivX codec developed by the guys who "hacked" 3.11 Alpha (the DivX 4.x codec is not "hacked" - it is a 100% legal and written from scratch). The DivX 4.x codec also offers backward compatibility with all movies encoded with the 3.11 Alpha codec (although 100% compatibility/performance cannot be guaranteed). Note that both the 3.11 and 4.x codecs can be installed on the same system (and 3.11 encoded DivX movies will playback with the 3.11 Alpha codec, while 4.x encoded movies will playback with the 4.x codec), so you can get the best of both worlds.
In other words, for the movie you download off the net, use the 3.11 Alpha version. If you have never used the DivX Codec to encode movies before, also use the 3.11 Alpha version, since most instructions are still for this codec (updated 3 September 2001 : there are now full instructions for using the DivX 4.x codec as well here). However, if you have experience with the DivX codec, or general AVI encoding, you may want to try the DivX 4.x codec (the codec on this page). If you are also concerned about the legal status of the 3.11 Alpha version, then you should use the DivX 4.x codec.
The DivX 5.x codec builds on the DivX 4.x codec by adding many new features and enhanced MPEG-4 support. Users familar with DivX 4.x shouldn't have any problems with using DivX 5.x, but may find that small bugs still can be found within this fairly early version of DivX 5.x.
