title_body: How does one wire an OSD-enabled external DVR into Fat Shark goggles?
upvoted_answer: I have an external fpv monitor with this DVR and if I watch the DVR live feed a delay in the video image is noticable. If the DVR does lock up while flying you are in big trouble. So I'd strongly advise against the "fly via DVR output" solution.
  
  But there is another solution: You can connect the DVR output to the usual AV input of the goggles (next to the power plug). On the bottom side of the googles there is a switch to turn off the receiver module. When the internal module is deactivated the goggles show the video from the AV plug.
  
  
  
  This picture shows the pinout of the AV cable (comes with the googles). I don't know if the DVR can be connected to the AV plug permanently or if this would cause interference if the module is active.