I think you'd be opening up a can of worms for yourself if you showed the drone video to law enforcement or your neighbor found out about it even though you stated you could see some of your stolen property from the ground without a drone. So in a sense you did have probable cause to want to investigate further but it's probably still illegal to do what you did... some sort of Peeping Tom law. And I can understand you wanting to see if other missing things were up there too but I think you could possibly get in legal trouble, and also have drama with your neighbor, if you share that video with law enforcement. More potential trouble for you than what it would be worth probably. But given that, you personally now have proof of what kind of person your neighbor is so you are fully aware anyway. Install a few security cameras around your home and signs that say the area is under video surveillance. That footage you can definitely provide to law enforcement when you film your neighbor stealing your property the next time and you'll also be able to get them for trespassing. Or just move away from your thief of a neighbor if you can.