On Mac OSX, QML VideoOutput may not stop playing audio after hosting QQuickView is set to a different QML file with setSource

This is a bit of an odd one; I don't consider it that serious as it's easy to workaround, but it may be a symptom of deeper problems...

I have a simple application which is basically a QQuickView which loads a QML file, and which exposes itself to the QML context as a "browser" object with a "load" slot which allows switching to a different QML file via setSource (typically in response to UI triggers). Code can be found at https://bitbucket.org/timday/qmltoy/ (code originally created to probe/demo QTBUG-42721).

If I start the application up with a QML file which doesn't host a VideoOutput item, everything works fine: I can browse to files with VideoOutput and then browse away from them and the video and it's audio plays as expected, when expected.

However, if I start with a QML file which hosts video, and then browse away to another file, the video's audio keeps playing! Further, if I return to the QML file with the video, I can hear two audio tracks!

I can't begin to imagine what's "special" about the first QML file loaded that it wouldn't completely clean up multimedia resources when the QML is torn down, while pages loaded later do. But maybe I'm doing something stupid in https://bitbucket.org/timday/qmltoy/src/ab0815f7a65f0963afce48f9f166abc665d2ad4c/main.cpp?at=default or https://bitbucket.org/timday/qmltoy/src/ab0815f7a65f0963afce48f9f166abc665d2ad4c/Browser.cpp?at=default

Only seen on Mac OSX so far. Also tested on Linux; that works completely fine. No other platforms tested yet (quite curious about iOS).