Soros is a very manipulative gentleman looking exclusively after his own interests. When he says A it doesn't mean it's true, it merely means that saying A benefits him the best.
Even if he's short the euro, it kinda seems that no single famous, connected billionaire can make or break the euro. It's, like, a really, really big, erm, thing. He ought to believe his bet to be correct rather than hope that him talking about it will move the market very much. So if he's indeed short the euro, I'd guess you're hearing his true opinion (which doesn't make him right, it's not like he's never lost money, it just probably means he's honest in this particular instance.)
The euro is bigger than GBP, but: You do know he broke the British Pound, right?
http://priceonomics.com/the-trade-of-the-century-when-george...
BTW, I found the interview rather trite; he's really full of it.