For some reason my safari will crop my youtube video, and it just zooms in. Even the controls are hidden inside the video player! I don't know how to fix it. I tried refreshing the page but the same thing!
Safari saves your zoom preference on a per site basis. If you accidentally bump the zoom, it will save the setting and use it in subsequent sessions. But honestly this sounds like a different problem, but I just think racking the zoom up and down (and resetting to default) would be one of the first things I would try.