Homepage messed up after installing Yoast SEO? Help pls.

Hi guys,

really need your help with this one. I have already tried to google the answer but I didn’t find the right solution.

Usually I solve all the problems by deactivating or deleting all the plugins one by one – until I found what caused the problem. However, I’m still not able to solve this one.

I have installed Yoast SEO like a week ago and I believe few hours later this problem occured. So I am not really sure if it is Yoast, but it might be. My homepage has started acting weird, the youtube video in the background of the first row has shrunk and has blank (black) spaces on each side now (screenshot).

In the seconds row, there used to be pretty big size sub-titles (screenshot) and now they act look like this, even though the settings shows otherwise.

The 3rd row is also acting weird but It’s the same story again.
I have tried to open the page in Yellow Pencil and I could possibly repair the problem there, but it’s not the “real” solution. There must be something else and I have no idea what it is.

Any tips? Thank you in advance.

The page I need help with: [log in to see the link]