I noticed in my video viewing that when I set the view mode to full screen, the message "Press Esc to Exit Full Screen" is never going away. I tried searching Google, and while many people have asked the same question, there was no clear answer.
Through some experimentation, I learned that in locking down my Flash Player (see New "Cookies" and your Privacy), I introduced this new issue. Apparently the Flash Player wants to store information as third-party content in order for the message to go away. You need to go to the Global Storage Settings panel and check "Allow third-party Flash content to store data on your computer." Interestingly, you can keep the storage setting on "None", and it will still work. (Remember, the Flash setting for your installation is reached by going to a website, with each tab having its own URL. There is no application you can open locally to make configuration changes. Learn more here.)
This seems like a real mistake -- to see a video full-screen, you have to allow any third-party to store a Flash cookie!? First, I don't see the reason any storage is needed to display text on the screen for a short time. Further, if required, why isn't the storage request coming from the same domain as the video? From what I gather, the full screen display, and therefore message, is a Flash Property. I suspect the third-party domain must be a Macromedia/Adobe domain, which also makes no sense. Macromedia/Adobe can track all our Flash usage, without any setting, so why make the 'call home' for full screen open yourself up to all other third-parties?
With the bloat of a Flash Player / Flash App, and the introduction of HTML 5 and native video support (see demo - browser must support HTML 5), perhaps Apple is onto something by not supporting Flash in their iPhone, iPod Touch, and new iPad.