One central thing of Plasma Active (soon to come in the desktop as well) is the use of share-like-connect
in this way the application advertises what content it has open. in the case of the mediacenter should be the current song/photo/video.

To do that there is a  QML component in org.kde.plasma.extracomponents called ResourceInstance that has just to be instanced once in the root item, then only thing to do is to keep its uri property synced to the currently playing item.

Reproducible: Always