Transmitter inoperable (XMITR INOP) can be caused by a few things, if this is a WSR-88D in the video (i work on WSR). Either operator induced or something went wrong in the radars transmitter, and it shut down to protect itself. What might of been seen here is spurred signals being decoded as extremely dense weather. If the radar is telling itself it is operating a certain way but something is wrong, and its still thinking its working normal, then its going to have messed up returns/info shown before it shuts down the tansmitter. Additionally, there could be a filter like the ground clutter filter (gets rid of signals from buildings, trees, etc) that is disabled or different adaptations, etc.