Hi Etoimos, The Mediarenderer its a control , not a loader, you must load the media with a control point (read the first post of original Media Render topic) or a smart app.
If you Media Renderer have a meda loaded , you can play, stop, change volume , if you have a list of music loaded, you can go previous o forward, but your speaker must to accept containers or your control point to be compatible (read the first post of original Media Render topic)
Think the Mediarenderer device like a cd player, you can play and control a cd, but you must first to load a cd. The cd player do not play music from nothing
The most common use to mediarender player its to play Smart Thinks messages, then several smart apps can send text messages converted to audio to play and continue your music
Example 1.
I use a control point to load music from my DLNA music server and now a music is playng, the front door has been opened, Smart Things detect the event and send a message to my speaker “the front door has been opened” and after play the message it continues with the music
To send the message ST needded a smart app that configures the message and the door sensor, you can use several smart apps, an exaple its Media Renderer Events smart app
I have added some radio stations to device handler, if you go to settings (little icon gear next the speaker name) you can select a radio station genre, with this you can play several radio stations if you activate the satation buttons from the mode button (the last button) and press the play station button.
I suggest you to read the first post of the next topic