How not to have click twice to pause youtube videos

Im a complete new Mac user.

When I have a youtube video playing in safari window, and I'm typing an email in a different safari window, I have to click twice to pause the youtube video, once to focus the window, and once again to actually pause the video. But if I double click the video it will switch to full screen! I have to click twice with a pause...

Is there any configuration I can change so that I only have to click once?

I Googled the problem and I see a lot about "focus follows mouse" plugins, but I'm not sure if that's what I need, I just want the click to go through, instead of a "dedicated focus click", because that doesn't make much sense to me.