For my eldest daughter, watching other people play video games (sometimes called "Let's Play" due to an early video channel that specialized in this type of show) is her primary form of entertainment. Almost any time that we see her relaxing, she is either playing a video game (usually one she saw on a "Let's Play") or more likely watching someone else play a video game. These videos are usually pretty entertaining, as you not only get the entertainment from the game itself, but also get to listen to the rather amusing banter of the people playing it as well. The really good commentators are actually more entertaining than the games that they are playing. For that matter, the great commentators can make even watching them play through a terrible game a downright hilarious experience.
I thought that this trend would end with my eldest child as my second child was not quite as enthused with the idea. That thought ended once my son started watching video upon video of people playing StarCraft II. I guess that this is more than just a fad.
I've watched a few videos, especially with the idea of improving my performance in StarCraft II, but the passion that some of my children have for this sort of view has eluded me. In the end, I would much rather play the game on my own than watch someone else, no matter how entertaining, play it for me.