Now rolled back to 188.8.131.522 I have video back (YAY!)
But now Mediabay is ghosting out. (BOOOO!)
Calling Media bay with either F5 or mousing menu brings up the track preset browser right hand pane (search results) and is blank on the window list
The only way to reveal the actual Mediabay was to shift+F5. Then the usual Media bay window would appear.
As a work around I removed F5 in key commands for “Open Media Bay” and assigned it F5 to Mediabay search.
Ditch prefs and clean install again?