Today Valve released an announcement clarifying the intended use of Steam’s trading system and OpenID API. Valve specifically notes that using “the OpenID API and making the same web calls as Steam users to run a gambling business is not allowed by our API nor our user agreements.”
As a reminder, per Twitch’s Terms of Service, broadcasters are not permitted to stream content that breaks the terms of service or user agreements of third-parties. As such, content in which the broadcaster uses or promotes services that violate Valve’s stated restrictions is prohibited on Twitch. Our Rules of Conduct lists other examples such as playing pirated games and playing on unauthorized private servers.