If you go to a page on www.chooseandbook.nhs.uk that doesn't exist, like this one: http://www.chooseandbook.nhs.uk/ajdoaijdjdad you'll get an interesting error message. The title is a stroboscopelike marquee text that flings across the screen. It's very frustrating to look at because it's a million times more animated than it needs to be.
BUT a fun thing about it is that it flashes by from left to right, right to left; like a the universal body language of waving your finger or turning your head to indicate NO. I remember that Red Hat used to have on it's display manager log in, that it shakes horizontally if you enter the wrong password. I liked that. It made sense and was not intrusive since it stopped quite quickly.
Anyway, it's an interesting to solution the NHS has taken to display this error message. I'm not going to forget it.
No I think it's Safari just doing their own implementation: <marquee loop="1" scrollAmount="60" behavior="alternate">
which is yet another reasont to stay away from using the <marquee> tag.