Cant see any sign that they are actualy investing in BTC.
The sign might be in the price rising since yesterday, maybe they know something in China we don't know yet
I think maybe he was being sarcastic. The 100 point rally led by OKCoin might be a sign.
That may be just the usual traders believing the rumor and acting on it. Or them expecting "the next bubble" by comparison with 2011 or 2013, and trying to get ahead of it. Or some other reason that we haven't heard of.
The rise was remarkable, but not unique. On March 03, 2014, the price wen up by +110$ from ~560$ to ~670$. (And it dropped again by that same amount, from ~580$ to ~470$, on March 27).