I'm building app using Javafx Webview, but I have problems with running any Youtube video in Webview.
The strange thing is that rarely it plays ok but more often it shows info "An error occurred, please try again later".
I tried to figure it out, so I made simple app using Youtube iframe API and firebug lite to show where is the problem:
Here is source of Main.java
Here is source of video.html
When I run it on my PC I see the result as below:

Error state 5 means "The requested content cannot be played in an HTML5 player or another error related to the HTML5 player has occurred.".
When I run this video.html file in firefox, chrome, or internal eclipse browser, everything is ok and always work.
I use JRE and JDK 1.8.20 but tried also with older versions, Windows 7 64 bit. I've also installed DivX - did not help. I tried on different PC (also win7 64 bit) and asked 2 people with similar config to run this - and it is not working. As far as I know there is everything ok on Mac.
Where can be the problem with that? Do You have any suggestions?