This site's Youtube embed thumbnail proxy

This forum proxies the Youtube thumbnail, which seriously reduces the load time of the page, and serves that instead of the embed.

Here is an example:

My website largely revolves around my Youtube channel and this feature would be very beneficial to me.

I assume this is custom made by eva, as I haven't seen this anywhere else. I don't see any Xenforo addons that do this, but I'm curious if maybe there is or how I could do this as well.

 

Thank you for your replies!