Learning new things is occasionally dull, but not when those things involve stunt cats and machine guns.
There have been other videos done on the physics of how cats land on their feet; this one is a bit more fun and the explanation is well put.
Cat Flipping - YouTube Video
The second video is a bit more in depth than the first and involves shooting a rifle, specifically an AK-47, under water. As you watch, note the strange behavior of the bubbles as the gas expands and contracts after exiting the barrel. Bubble bounce is a phenomenon one can observe while scuba diving when bubbles the diver exhales briefly undulate before "stabilizing" on their shaky rise to the surface. The gas of the gunpowder explosion illustrates this phenomenon to the extreme. The host also explains cavitation; something that happens to the hull of a submarine
Underwater Gunfire - YouTube