Youtube not always working in Safari

I've been having problems with playing YouTube videos in Safari recently. It only happens on the website itself (the same video on Facebook works) and on random videos.

What happens is that I get a black video box with a swirling center (see image)
screen-capture-5.png

The it continues doing this while 'playing' for 4 seconds and then goes back to the beginning and starting again. Constant loop.

Not doing this in other browsers.

Can someone help me out with this?