Windows: http://downloadfinder.intel.com/scripts-df-external/detail_desc.aspx?dwnldid=2846 (the download button is at the bottom right of the page)
Mac OS 8 and 9: http://www.defyne.org/i263
Mac OS X: http://www.birthday-buzzer.com/other/i263/i263.html
i.263 is Intel’s implementation of the h.263 standard for its webcams.
The codec used to be an automatic download using Windows Media Player 6.4 and higher (http://codecs.microsoft.com/codecs/i386/i263_32.cab), but Microsoft removed it.
For a long time SlaveTrainer’s page was the authority on this, but it’s a bit out of date now. It does contain good instructions to make the codec work in Windows NT 3.51 though.
As stated above, the codec can be obtained directly from Intel here http://downloadfinder.intel.com/scripts-df-external/detail_desc.aspx?dwnldid=2846
For a very long time no i.263 solution existed for the Mac. Fortunately, that changed thanks to the individual efforts of some.
John Dalgliesh made a port to Mac OS 8 and 9 using ffmpeg libraries. His QuickTime plugin is available here http://www.defyne.org/i263
Sean Watson updated it to work for Mac OS X. http://www.cam.org/~cwatson/i263/i263.html (I believe you’ll have to e-mail him to get the binaries)
If you’re seeing a red X during installation and it stops, that means you’re using the old version of codinstl.exe (2.55.014) on a 32-bit system (Windows NT 4.0, 2000, XP, 2003, Vista). Version 2.55.014 of the install will only work on Windows 95, 98, and Me. Use the current version 2.55.016 (link at the top of the page) instead. On Windows XP you can force version 2.55.014 to work by right clicking the file, clicking the compatibility tab, and choosing Windows 95 compatibility mode.
Keywords: i263, I263, i.263, I.263