The "Stream" button the front of all Videon devices is used to enable/disable a stream.
The current functionality of this button is to enable/disable RTMP 1. Nothing else is currently controlled by the "Stream" button.
Regardless of whether the device can actually stream RTMP 1 or not, RTMP 1 will be enabled/disabled by the "Stream" button.
For example, if RTMP 1 is configured to stream to YouTube, RTMP 1 is turned off, but no video source is connected to the Videon device, pressing the "Stream" button will enable RTMP 1. RTMP 1 will then wait for a valid source to be connected, then start immediately since RTMP 1 is currently enabled.