Yes, if you setup a camera and try the same shot 20-100 times eventually you will make it. It's not amazing, it's just doing something over and over again until you get lucky.
webm is nother audio/video container file format like mp4 or avi. It's a pretty new one that is open source, and it's designed primarily for streaming.
"web media" is the source of the name, coined by Google.
But they are flavour of the month all over the net so I guess there's no avoiding them.
Most next generation browsers should support them natively. Hopefully. Right now most browsers aren't even playing the sound, just the image. Webm has sound.