OSMF 1.6 breaks spark.components.VideoPlayer in Flex 188.8.131.5286.
It causes the VideoPlayer.videoObject to always be null, even after waiting for mediaPlayerStateChange to be "ready" or "playing". This breaks any functionality that needs the source video's original size. (VideoPlayer.videoObject.videoWidth, VideoPlayer.videoObject.videoHeight)
Once I rolled back to OSMF 1.5, it worked again.
Hope this helps someone.
you could use mediaWidth or mediaHeight properties of the mediaPlayer to get those values.
I think you have run into a stageVIdeo related issue - are you sure that stageVideo is not active?
My recommendation is to raise an issue at http://bugs.adobe.com/jira/browse/FM , providing an example code that replicates your issue.
Thank you in advance,