No fullscreen button/hotkey with Viewtube on Dailymotion.
I tried this for dailymotion because it has an atrociously bad player.
But the lack of a fullscreen button and shortcut makes viewtube also really difficult to use.
I can only get into fullscreen via the context menu, which is really cumbersome.
What video player do you use? If the default (HTML5), select "HTML5" from the second menu.