title_body: Why does the video cut out on HX-100 drone?
upvoted_answer: This sounds like a loose video wire from your camera to your flight controller.  Since you still see OSD, but a gray screen, it indicates that the connection from the flight controller to the VTX is good (that's why you are seeing OSD), but the gray indicates that something is wrong on the camera end.
  
  A warm camera is a little alarming.  A warm VTX is normal.
  
  I would check all of your connections to your camera.  If they all seem fine, then the problem could be the camera (the warm camera seems culprit to me).