As Peter has said, it needs to be mounted properly.
I have a pax hold the camera, but when I am solo I strap the tripod down with the rear seatbelts and bungee cords and start recording as soon as I am settled in my seat. That way I can forget about it and it records my pre start checks and the entire flight from picking up the checklist to unstrapping and getting out.
That will at least provide the AAIB with something to go on if I don't make it back one day.