Sometimes when editing slides with video in SSB the frame preview does not appear

One of the new enhancements to SSB is the still frame preview of videos when editing slides with video in SSB. This is done by capturing a frame from the video to display as a still preview.  Sometimes when editing slides with video the still frame preview does not appear because it was not able to capture a frame in the time allowed. 

If you simply select another slide in the slide show, re-size the edit window or otherwise refresh the display the preview frame should appear.

You may also see something similar to this when the video in use has several seconds of black for a lead-in.  It will appear in the still image preview that there is nothing there when it is actually a black frame of video.  This is not an issue, but rather a limitation based on the video being used.  

(SSP18)