Twitch Recording (instead of Twitch Viewing) Application Signature?

With FortiGate 5.6.6 I had Application Control blocking Streaming types, which included the signature for Twitch (39771).

Noticed this was not blocking people recording/streaming Twitch using OBS (Open Brodcaster Software) at all.  In fact, the logs would show the Application as "Twitch" and that it was allowed (using TCP/443), despite the Application Control profile disallowing it.

Does anybody have a signature for OBS or Twitch that might block this?

I have a partial workaround, which is blocking TCP 1935 (used for initial RTMP to Twitch servers) and blocking twitch.com by web filter, but an application signature would be great.

Thanks.