Last week, Valve added another feature to its ever-growing Steam gaming service: Broadcasting. Don't scoff—you might find yourself doing it, too.

Videogamers sharing their experiences via live streams, often unedited and without any additional polish, has become a surprisingly captivating form of entertainment. Amazon recently acquired Twitch for nearly $1 billion; YouTuber PewDiePie makes millions off his videos. This week, South Park skewered the "Let's Play" phenomenon.

Valve's approach to broadcasting gameplay over Steam, currently in open beta test, differs from the Twitch experience in a few key ways. Twitch wants you to become a gaming personality, encouraging streamers to promote themselves and develop a loyal following of channel subscribers.

But even before you reach that level, you have to make the conscious choice to start streaming on Twitch. You have to register a new account, open Twitch in your browser and start broadcasting. Streaming via PlayStation 4 and Xbox One is a bit less frictional, but you still have to make an account and tell the system to start streaming. You have to decide to become a streamer, then go try to find viewers.

Steam, in a classic example of Valve's counter-intuitive thinking, flips the equation: It creates would-be viewers, then looks for broadcasters.

Once you opt in once by setting up your broadcast settings—high-level things like who can watch (no one, friends only, anyone)—you're done. Now, any time you play one of the thousands of games on Steam, your friends can see what you're playing, and request to watch.

Once someone has put in a request, the system automatically sets up the broadcast and a chat room so viewers can talk while they watch you. As the player, you can ignore this entirely and close the streaming overlay, just going about your business, or you can use the overlay to engage with anyone watching.

It's unlikely that any Twitch regulars will switch over to Steam—there aren't any built-in methods for monetization or building up a following. But for us casual players who don't want to deal with building a zealous fan base, this is a perfect way to let some friends watch you play.

Don't think anyone wants to watch you play games? You never know when you'll get that first request.