I know in hind sight you always think of things that you should have done different, but in the terrain that you were flying in and from the map you displayed with locations, it looks like you may have been within VLOS when the bird went down so I would have just walked out towards the last known position and done a quick ground search first. When things are flat like they appeared to be in your video, you can usually spot things a lot quicker from the ground. If it had been a forest or more rugged terrain, then walking may not have been the first option.
Whether you were walking or doing an aerial search, you definitely should have done a grid pattern, taken things a little slower and when flying, stayed a littler lower to the ground and kept the camera at the same position/angle. Using the Mavic was a good idea, but you may have been a little more efficient if you had used Litchi or Drone Harmony and set up a waypoint mission. You can definitely over look things when you are doing aerial searches if you are the PIC because your focus is more on flying, not searching. That is why when doing an aerial search from a plane, you almost always have a spotter or two or three. The Pilot hardly ever sees the target (if it is small), unless someone else in the crew points it out to him, or unless it is in the Movies.
Glad you found your Phantom, and I wasn't saying all this to be critical, it is just for others who read this and may be in the same situation at some later point searching for something whether it is another downed aircraft or a lost person.
