In the event of a failure in the real-time feed, the show can be made to switch into a default playback mode using the IntelligentSource™ feature of Delta (from version 2.7). This will detect from the video signal if the real-time feed is no longer live and switch in a replacement feed so that a show flow is maintained.
IntelligentSource must be enabled in DeltaGUI, Display > Output Setup:
It can then be enabled in any capture resource, in its Resource Editor, Timeline tab.