.If you have a pre-recorded video that you want to share with your audience, you can add it as a source. Once the file is added as a source, you can route an input to it.
To add file sources to your inputs:
1. Select
the Recorder, expand the Recorder, and then click the Open List of Inputs for
Selected Recorder button .
2. Click
the Add Input button 
and select File from the Input
Type menu.
3. Click Choose File and navigate to the file you want. Click Add Input(s). The file is now listed in the inputs.
Add video file sources