In video games, spectating is new form of advertising

The rise of online audiences watching video gamers stream themselves playing isn't simply a new form of entertainment seen by millions. It's also driving video game sales, and drawing the attention of federal regulators.

A study released Wednesday by live streaming company Twitch attributed 25 percent of sales of releases like the fighting simulator Punch Club and the kill-or-be-killed multiplayer game The Culling to those games being played on Twitch. The study found that viewers were more likely to buy a game within 24 hours of watching a stream of the game in action.

"There's a clear relationship between viewing and purchasing behavior," said Twitch data scientist Danny Hernandez, who studied users who connected their Twitch account to online game retailer Steam for increased social interaction.