Transcription
If you place the boiled egg on top of the bottle with paper burning inside, the fire will heat the air inside the bottle, making it expand and a little bit will escape, forcing the egg to jump.
But once the inside of the bottle cools down again, it will be missing the lost air since the egg is blocking the entrance. This makes the air pressure inside the bottle lower while the pressure outside is higher, which will start to put force on the egg. And when it gets strong enough, it pushes the egg into the bottle.
To get it out, just blow warm air inside to fill the bottle. And when the pressure gets too high, it will push on the egg again, forcing it to pop out in one piece.