So, putting this in the perspective of the LPer: could a Let's Play possibly fulfill the requirements to violate copyright law? The first requirement is a no brainer, since most LPs easily take up ten or more "public performances", but it's the bit about needing to exceed a certain amount of monetary damage I'm interested in.
The video at the top of the thread has an interesting point about video game companies wanting LPs and reviews out there, because it helps spread word about the game. But, I can also see that LPs decreasing the amount of people who buy or play the game, because they've just watched all of the important bits already. I'm guilty of this myself: I hate playing horror games (because I'm a wuss), but I like watching LPs of horror games. So, I watch the game get played, and I'm satisfied: I didn't buy a copy of the game, and have no desire to do so because I've already experienced the bits that I'm interested in.