The footage is likely staged as a publicity stunt to create hype about some Metal Detectors, as you pointed out in the OP. At the very least, it creates buzz that might attract those interested in fringe things like UFOs, the paranormal and other beliefs that also align with dowsing. They don't appear to be selling normal metal detectors, rather some sort of detector-dowsing hybrids of their own design.

They may wait a bit and gauge reaction to their video. If there is enough positive interest from the target audience, I wouldn't be surprised to see future detector-dowsing hybrids infused with alien technology on their website.

As for drones, I doubt one is even needed. Most of the footage is purposely shaky, random and sketchy quality, but most of it looks like a simple balloon. There is a helium balloon just rising. Then there is one descending, possibly with some weights on it or it was hit with a pellet gun.

You can scrub back and forth with a YouTube video frame by frame using the < > keys after pausing. Note that the descending balloon starts to go behind some brush:

Then a few frames later, the camera operator completely loses the balloon as they pan down and screen left:

When the operator gets back on the balloon, it's now moving screen left:

Not saying it's 2 different balloons, but it's possible. It could be a very light weight ball under a drone, but whenever an object is "lost" on the video and then does something different when it's reacquired, there is the possibility of manipulation. In fact, as the camera is wildly moving down and to screen left, this frame is exactly the same for 3 frames in a row with zero movement:

After 3 of the same motionless frames, it looks like this as the camera starts moving again:

So, as the camera is moving all over the place, having lost the object the operator managed for 3 frames to be completely motionless and hold the camera absolutely still, before once again moving it around wildly. Or something is going on and some sort of manipulation is taking place.

EDIT: The back and forth between the silver ball in the lab and the video of the silver object reenforces to the viewer that they are the same object, when they likely are not and don't have to be.