Cannot play embedded YouTube videos in Safari on MacBook

For some reason, I'm completely unable to play embedded YouTube videos on my new MacBook Pro. I've had this computer for a little over a week, I don't have any extensions installed and I've cleared my cache, I'm not sure what else to do. I'm using Safari, and to my knowledge I haven't screwed with anything that would make this happen. I can play YouTube videos just fine on the website, but it won't play whenever they're embedded- I get this error.