What is a Let's Play?
Basically a "Let's Play" is player playthrough of a video game. Watching these you can learn new ways of finishing a game, learn whether you would buy a new game or not, or just for some of the sheer hilarity that evolves when others dictate their feelings and thoughts while recording.
How are they made?
Usually through
fraps and a video editor of course. Mics make nice additions as well.
Because these "Let's Plays" are pretty straight forward from there I'm just going to post one of the best Lpers in my opinion, but you may disagree. Either way it should give you an ideal of what to expect.
Bashur