Where are people watching videos on YouTube? A little while ago, the majority were on desktop, but now the company says that half are tuning in from mobile devices like phones and tablets. On stage at the Code Mobile conference, YouTube CEO Susan Wojcicki said that metric's grown alongside the popularity of its app on places like Apple's App Store, where it ranked among the top apps last year.

One thing Wojcicki did not want to talk about though was how the company didn't manage to strike a deal with Twitch, which was snapped up by Amazon instead. "I think YouTube has been lucky because we have a lot of people who come and watch games. Kids — I've experienced this at home — show how engaging and interesting this can be, but I don't know if I can really say more," Wojcicki said, adding that the company was "continuing to invest in the gaming area."

YouTube's unannounced subscription music service still under construction

Wojcicki was equally mysterious about the company's long-rumored music project, which was reportedly set to be unveiled at some point this month, but that is apparently still in the works. "We're working on it," Wojcicki said. "We've been working on it, and I think there's a lo of opportunity. It's amazing."

Wojcicki took over as YouTube's CEO back in February, after running the company's advertising business. She was employee No. 16 at the company, even housing it in her garage back before the company had its sprawling headquarters in Mountain View. She's also the sister of Anne Wojcicki, the CEO of 23AndMe, and who is married to Google co-founder Sergey Brin (though the two are separated).