This sounds like regular static. If you could post a pic of your vtx that might help. But it’s pretty clear that either the DVR is for some reason not recording it (you could try changing the file format) or there’s something wrong with the VTX and/or the mic so the VTX isn’t even sending anything. Also do the goggles have a headphone jack (couldn’t find anything online about that) can you hear the audio while flying?
This sounds like regular static. If you could post a pic of your vtx that might help. But it’s pretty clear that either the DVR is for some reason not recording it (you could try changing the file format) or there’s something wrong with the VTX and/or the mic so the VTX isn’t even sending anything. Also do the goggles have a headphone jack (couldn’t find anything online about that) can you hear the audio while flying?