When you want to capture videos in a presentation, you would normally create a new source in Windows Media Encoder and add the VGA2USB device as a video device.
When Windows Media Encoder doesn't detect a VGA signal on the VGA2USB device, it will return an error 'One or more codecs required to open this content could not be found' and will not allow you to store the configuration. To solve this issue you can configure VGA2USB to send a static image if no VGA source is available. To do this you need to configure VGA2USB.
Startup the VGA2USB application on your desktop (the green e icon). (If you are on windows7 be sure to run this as an administrator to persist the settings in registry).
Choose Capture and Configure Device and switch to the Directshow tab. Check the Fix resolution checkbox select a resolution you want to use (eg 1024*768). Then check the Default image checkbox and browse to an imagefile you want displayed by default. This image file needs to be a uncompressed bmp file.