You're missing a lot.

I've done exactly what I described in my comment for the last 8 months: it's been a UI feature of Tesseract since last October.

It proxies any image or direct video from any source you haven't blacklisted. If you have the proxy option enabled in your settings, all image URLs are re-written to go through the proxy. If not, then it uses the regular URL directly. It also caches with an admin-defined policy.