I doubt anyone (beside me) is doing this, but since I mentioned I was it is worth a notification.
I use a curl/wget script to download the mp4 vids from the camera to nearby laptop at the same time I am recording/capturing the road. I have found that when this process is active some frames are being lost and the resultant output upsets the mapillary tools geo-encodng process. Position errors have crept in mid way through each video but correct by the end.
In my case I am running the Mapillary firmware dr900s-1ch_v1008_psn_190315 at 2 frames per second (the default/commonly used is 5 frames per second) so I should get 120-222 frames per file. I have been getting 109-110 frames of which 60-61 are always the index type. ie it only drops B frames.
I still use the WiFi download facility at the end of driving day. Each mp4 file is roughly 50MBytes and it takes about 10 seconds to download a minute of capture. It saves dropping/losing the SD card or damaging the socket.
If you are considering doing concurrent downloading it might be best to check your setup for loss. One easy way is to check the video with ffprobe to make sure it really is 2 or 5 (or 30) frames per second. My “bad” system was showing 1.8 when the download was concurrently running.