If you use GotoMeeting to record video of the shared screen, make sure that you DO NOT use G2M3 codec. It does a great job in compressing the size of the video but it is not compatible with OSX or any OS other than Windows.
I recently received a client application screencast wmv encoded with G2M3 codec. Had hard time figuring out the way to play it on Mac OSX. There is no codec for mac and normal work around you see in the first page of Google doesn't help either.
I tried Handbrake, VisualHub, FFMPEGx and MPEG Streamclip for Mac without any luck.
I can't export the audio of the file to MP3 even the almighty Super failed.
Take away: Never encode in G2M3. If you do then, please use Expression Encoder to convert to wmv that can be played in other OS (limited support but at-least you can view).
P.S: This post doesn't fit in a tweet, and take away alone does not convey it all.