Comment 30 for bug 723831

Also remember to inform users of Adobe Flash Player EULA legal problems . The Adobe Flash Player End User License Agreement prohibits reverse engineering and more. Therefore developers cannot develop a competing Flash player if they've accepted the Adobe Flash Player EULA.

See also
https://answers.launchpad.net/ubuntu/+source/flashplugin-nonfree/+question/135400

The YouTube HTML5 Video Player works without the Adobe Flash Player plug-in.