With Firefox 22 (released in late June 2013), SkipScreen provokes a stream of dialog boxes that declare “SkipScreen cmp: Error: Illegal operation on WrappedNative prototype object.” Complaints to the Mozilla.org plugin page go unanswered. The SkipScreen 'blog has not been up-dated since 14 March 2012. The FAQ is silent on the problem. And my guess is that nothing useful will be said here, anytime soon.