So a classic sig double action or 1911 wouldn't be effected? He video says striker fired specifically. Cocked and locked I'm not sure how you would make this happen.
Hammer-fired guns have a similar issue if you drop them directly on the hammer (or on parts that can move the hammer) when the hammer is cocked. When the hammer is not cocked, there's no available energy in the firing mechanism to discharge the gun. Striker fired guns are effectively in the cocked state at rest, though. In a "cocked and locked" state, you would need the drop to disengage or overcome the safety, not just the normal trigger mechanism.
Not affected in the same way. The original M1911 design has a floating firing pin held back only by spring tension, so in theory it might be possible to get it to discharge without pressing the trigger by dropping it straight onto the muzzle from a sufficient height. This is so unlikely in practice that it's not a real concern. Some newer variants also incorporate an extra internal safety that blocks the firing pin from moving.
