Hi there,
There seems to be a problem with your theme installation and the theme seems to be corrupt. I checked the generated HTML code and the columns should be as you said:

Now the problem is the generated CSS code of the theme is nowhere to found regarding the column system you used. Please kindly follow the general troubleshooting steps below:
- Ensure everything is up to date according to our version compatibility list here. Please follow the best practices when updating your theme and plugins. Click here for more information.
- If you’re using a CDN, please clear the CDN’s cache and disable optimization services.
- Test for a plugin conflict. You can do this by deactivating all third-party plugins, and see if the problem remains. If it’s fixed, you’ll know a plugin caused the problem, and you can narrow down which one by reactivating them one at a time.
- Remove custom CSS and Javascript from the options or Child Theme and test the case.
Regarding the video fullwidth problem, I checked the front end of the website and see a max-width: 500px in the code:

I am not sure if it is a generated code from the options of the elements you use in the Cornerstone or something that you added to the custom CSS section.
I suggest that you focus on the problem on Chrome first to make everything work then we will tackle the Safari one.
If you still have problems kindly get back to us with the URL/User/Pass of your WordPress dashboard using the Secure Note functionality of the post to follow up the case.
Thank you.