Allen McKenzie

You can disable the recommended video section when you share a video but the videos in that section are custom tailored to that specific visitor, their YouTube watch history, and video that are related (in one way or another) to the video being embedded.

In short, you can’t customize that to show your videos in place of the ones that YouTube provides.

What are you trying to accomplish exactly? If you are just wanting to have separate groups of listings then the best way to do this would be to create a custom taxonomy and use that to separate listings into their own groups.

80MB is a pretty sizeable database table to run a find and replace on. You might find a solution using SSL Insecure Content Fixer to get around the mixed content issues.