On a related note, see Video Game Addiction Tries to Move From Basement to Doctor’s Office (NYT)
"Twitch began in 2011 as an offshoot of Justin.tv, a lifecasting site founded by two Yale graduates, Emmett Shear and Justin Kan. They started the platform after they found that viewers were more interested in watching their lifecasters play video games than eat or sleep. Big tech companies came courting, and Amazon beat out Google.Amazon Tightens Grip on a New Medium: Live Streams of Video Games -- NYT
In the four years since the sale, video gaming as a spectator sport has gone mainstream, and Twitch has captured the majority of those who want to watch it live.
For the dedicated fans, the live, freewheeling sessions on Twitch have the appeal of a major sporting event crossed with a talk show. The interaction between the host and viewers is one key to the site’s success, making for an involved viewing experience that is markedly different from the prerecorded and edited videos of game sessions that have long been popular on YouTube."