See http://www.techsmith.com/snagit.asp?CMP=KgoogleStm

If you don't have these codecs on your computer you can get them at:

DivX   http://www.divx.com

Quick Time   http://www.apple.com/quicktime/download/win.html

Microsoft   http://www.microsoft.com/windows/windowsmedia/player/faq/codec.mspx