Many players stream to Twitch.tv from Nostalrius and I enjoy watching them.
Twitch's "Rules of Conduct" say that you are not allowed to stream pirated games on private servers but Twitch will (probably) not take action unless the publisher (Blizzard) file a complaint.
This means you
can get banned + IP banned but it's unlikely for a small channel.
Source:
https://www.twitch.tv/p/rules-of-conductRules of Conduct wrote:Unauthorized Rebroadcasts & Other Copyright Violations
Uploading any content that you do not own, do not have the rights to, or are otherwise not authorized to use may make your account liable to DMCA takedown by a rights holder. This includes, but is not limited to: rebroadcasting other Twitch broadcasters, playing pirated games, playing on unauthorized private servers, and uploading content from other sites.
Interesting thread on reddit:
https://www.reddit.com/r/Twitch/comment ... _bannable/