UPDATE: VLC Player v2.1 supports the current GoToMeeting codec. This means Mac users can now playback GoToMeeting recordings that have not had the codec removed or been converted to another format: http://www.tuaw.com/2013/09/26/vlc-for-mac-gets-4k-support-dozens-of-new-features/
As you may already know (or have just discovered), when you record a GoToMeeting, GoToWebinar or GoToTraining, a codec is applied to the WMV file. The codec is used to compress the size of the recording, but unfortunately it can get in the way when you try to edit the file.
The good news is that you can always remove the codec from your recording, here are the 3 methods:
Configure the GoToMeeting Recording Preferences to automatically remove the codec at the end of the session. This is handy because it’s an automatic process but the down side is it ties up your PC right after your session.
Use the new Transcoding Wizard provided by GoToMeeting.
Use the free Expression Encoder from Microsoft as documented here to remove the codec and edit the recording. The benefit of this method is it lets you remove to codec whenever you want plus you can edit the recording. The downside is the free version of this application does not let you convert the recording from WMV to another format, but there are other free applications you can use to achieve this.
If you are having trouble with this method, it may be due to changes made in GoToMeeting v5.4. Please see this new post for a solution: https://glenndcitrix.wordpress.com/2013/02/22/using-microsoft-expression-encoder-with-gotomeeting-v5-4/
I would like to thank everyone who have left comments, and shared their own helpful tips!