How do I watch the video in fullscreen?

I have found the video I want to watch on a website using my android phone. The problem is, the video screen isn’t fully shown on the page, only about less than ¾ is shown. I tried using the rotation technique to get the whole screen but it only show a little more than ¾ of the screen. Pinching the page to enlarge/minimize doesn’t work. Tapping the screen twice too won’t allow me to watch it in full screen. The problem here is that the full screen button is on the far right edge of the video screen and there’s no way for me to reach that button. What else could I do?