Good question, darock, but no. I guess that I didn't explain it enough. Certainly the bottle has been cut off to insert the plug with the narrow end of the plug toward the bottle top. The air pressure is developed when air is pumped in due to the tight fit between the shrunken bottle and the plug, and the air pressure quickly expands the bottle area around the plug to break loose the plug from the bottle.

Hope that this helps you understand the process.