A DESCRIPTION OF THE PROBLEM :
This issue is still happening with JDK 13 and JavaFX 13.0.1


CUSTOMER SUBMITTED WORKAROUND :
Typically catching the error, stoping and disposing the MediaPlayer, wait, then create new MediaPlayer will result in media playing. Even with this work around many times will continue to receive the gstream error of ERROR_MEDIA_INVALID on each retry. ([com.sun.media.jfxmediaimpl.platform.gstreamer.GSTMediaPlayer@6a48101f] ERROR_MEDIA_INVALID: ERROR_MEDIA_INVALID)

FREQUENCY : always