In reply to Paul Phillips - UKC and UKH:
I don't know that it's rendering wrong, it looks like it's doing what it's supposed to. I see it in chrome on windows and linux and a chrome-derived browser on android. It's masquerading as https://cdn.ukc2.com/core/1px.gif but that's clearly not where the animation lives.
Edit: it's nothing technologically out of the ordinary, just another flickering animated banner ad, but the colours they've chosen are especially annoying and much more irritating than all the others.
Edit again: followed the trail of crumbs and found it's this one https://cdn.ukc2.com/ads/html5/11714/h264.mp4 that I'd like to burn with fire. It's working fine, and that's the (well, my) problem.
Post edited at 09:35