5by, founded in 2012, bills itself as "curated, free and awesome." Its service is designed to suggest videos you'll like based on previous choices and reactions, somewhat like the thumbs up or down options in Pandora.
StumbleUpon CEO Mark Bartels explained the deal to TechCrunch as “a directional bet on mobile and video" as the future of both advertising and web content consumption. The entire six-person team will continue to develop 5by as a standalone product, though they'll now be working from StumbleUpon's San Francisco office rather than their current location in Montreal.
StumbleUpon, which was founded in 2001, announced last week that it expects to grow revenue between $35 and 40 million this year. This is the company's first acquisition.