Sorry for bumping into an excisting thread for the second time, however.....
I'm getting the same error message.
I have added Netflix as a webpage (because the official one is not working properly).
It will still open after the error message and I can start a movie, but I can not set it to full screen.
Normally when you move the mouse cursor a bit the bar with volume, stop/start etc pops up and you can sellect full screen. On my other pc it works like this and there I also do not get the error message. Their both fully updated windows 7 machines with identical and latest versions of JRiver (19.0.67). In both explorer is set as web browser, I can also not find any difference in setting between the two.
I think this full screen issue is related to the browser engine error message, but I could be wrong.
Well I hope someone found a fix or can point me into a direction to solve this.
I know the easy solution is to just watch in a web browser but I very much like to stay within MC (love it by the way)
regards
Ron