That plugin has always caused havoc with animated GIFs.
The resize algorithm is the kind that you must expand to see the detail (few people would make a needlessly large animate GIF) and they bounce back to the small size each time it loops (many animated GIFs are on a tight loop) which is usually before you could even scroll to fit or center it on your screen.
It should stay expanded if I click the title to expand and I am against implementing it until it does.