Observer Wireless Signal

So I was playing Minecraft trying to make a Redstone flying machine and when I was there was air underneath the observer and under the air, there was a piston and when I put a block on top of the observer it made the piston move through the air I tried some other Redstone things that would do the same thing but most of them didn't get a signal except for Sticky Pistons, Pistons, Dropper, and a Dispenser, here's a video of it actually happening: