More than 5,000 people across the globe recently logged on for the webcast of a Commodity Futures Trading Commission (CFTC) public meeting—not a significant number by Internet cat-video standards, but by far the largest online audience that one of our meetings had ever attracted. Viewers in Guangzhou, China, outnumbered those in Washington, D.C.

What drew them? The CFTC’s Global Markets Advisory Committee on Oct. 9 was discussing virtual currencies, Bitcoin in particular. The viewers’ comments sent a clear message to federal...