Pause the video in a side view.
I actually did take a photo of the mount but of course I don't have it with me. If you pause the video on a side view you can see the tail mount. What I did was cut a hunk of foam to fit aroound the fin. I taped sandpaper on the tail over some plastic and used the actual shape of the tail to sand the inside of the foam so it was a tight fit on the fin. I gave it a faired in shape and then I covered it in fiberglass. The inside fit tightly to the fin. I filled the inside with silicon rubber and put a piece of plastic over the fin. I stuck the mount onto the fin and let the silicon rubber set up. When I fit it to the rudder it is really snug and does not want to move. The fin gets larger as you move down from the top, so I just lower it till it's tight. I then just use some blue painters tape just to keep it from falling off. You can see the painters tape in the video. I also fiberglassed the GoPro open back to the mount. When I want to use it, I snap the front of the enclosure to it and tape it on. The sound is from a seperate voice recorder in the cockpit. If you want to see photos of the mount itself I can get them for you later today.
FP Wood Prop