Then what does open mean? To me it means to provide an API on an equal footing among the various platforms. If Google is providing access to secret Web service APIs to their Android and iOS Youtube Apps, but not to Windows Phone, how is that open? Requiring to show ads is still understandable, but requiring HTML5? Why do they care if it's HTML5 or something else? It sounds fishy, and Google should come out with a real reason for requiring HTML5 if there is one, after all they call themselves open.
It is probably well within their rights to screw around since it's their stuff, but lets not pretend it's open. Didn't MS get lambasted for private APIs in Windows? Why does Google get a free pass now and get away with calling itself open?