Handicraft construction of a vacuum bell, various experiments. With the bottles, the vacuum pump is removing the air inside, creating a pressure difference inside the bottle and the surrounding. When the pressure difference is stronger than the plastic, the surrounding air pressure collapses the bottles. The surrounding air has a pressure equal to 1 atm, or 14.7 pounds per square inch, which is pushing against everything. When the air is sucked out of the bottle, even a small drop to say 10 pounds per square inch, there's a difference or a force of 4.7 pounds per square inch pushing against the bottle. This is a strong force. After that he simply reverses it, increasing the pressure inside the bottle and inflating it again. As you can see when he puts the deflated bottle (with a lower pressure inside), in the vacuum "chamber", the pressure of the surroundings are equalized to the pressure inside the bottle. When the pressure difference is equal, the plastic will bend back to normal. When the water is placed inside the vacuum chamber, and the pressure of the surroundings are reduced, the water actually boils, yes, it reaches boiling. But it's important to realize that the water do not get hot (it actually gets slightly colder). The only reason why water stays a liquid to begin with is because the air is pushing it with a strong force, forcing the water molecules to stay together. Boiling is actually defined as when the vapor pressure is equal to the surrounding pressure, the vapor pressure being force exerted by liquid "wanting to become a gas", or how readily it can vaporize. At lower pressures water boils at lower temperatures. With the polystyrene balls, there's a fan inside the chamber which is blowing them around. As the air is removed, there's no longer any air for the fan to move around, and no air exerting their force on the balls, so nothing happens there. With the bell in the chamber, you have to realize that sound is carried as pressure changes in air. So sound necessitates air to move. When the air is removed, no sound can travel, so you won't hear anything.
With the filament bulb. Most pure metals will react with oxygen in the air, forming metal oxides, one example being rust (iron oxide). The reactivity of a metal to oxygen increases as the temperature increases. A red hot glowing thin metal wire would react with air instantly, and "burn out" or oxidize. This is why filaments are covered by a sealed glass bulb, which are not actually at any reduced pressure, but simply filled with an inert gas (and the oxygen removed), that will not react with the metal. The vacuum removes a lot of the oxygen, reducing the rate at which is oxidation can occur, and the bulb don't burn out immediately. * Compressor model: LG Electronics Inc. NK 164 PAB - LRA20 - 1PH 50Hz 220-240V