Loituma Girl (aka Leekspin)

Featured on mental_floss as "Viral meme all your friends already know about", Leekspin is an audiovisual braincracker of extraordinary magnitude.

Let me emphasize my belief that mentalfloss's warning "Do not, repeat, do NOT click on this link if you actually have something even slightly, vaguely important to do today, or if you are at all worried about maintaining your sanity." is putting it far too mildly!

Tell me how long you kept it spinning.

Heck No! (I'll Never Listen To Techno)

I rarely check out any of YouTube's featured videos - I think we can pretty safely assume 99% of them are crap.
But the short text for this one got me interested - and I didn't regret clicking!
"A "What if?" scenario of Robots taking over and destroying the Earth is told on a Lite Brite."