The CEO of Musical.ly, the lip syncing app that’s become a major hit with youngsters worldwide, has defended the way it manages its users, some of whom are younger than 13 years, while also revealing that the service now has over 40 million monthly active users.

Alex Zhu, co-founder and co-CEO of Musical.ly, told an audience at TechCrunch Disrupt London that the app now has over 130 million registered users, 40 million of whom are active on a monthly basis. More than 12 million new videos are uploaded daily, he said.

That’s an impressive stat for the U.S.-China company, which pivoted to its current form after initially being an educational platform and nearly running out of cash, but fast growth means increased scrutiny around thrusting young people into the spotlight. Musical.ly doesn’t force users to provide their date of birth but many are aged under 13 and freely contactable, putting it at odds with the Children’s Online Privacy Protection Rule (COPPA) which forbids online contact information for under-13s.

“We could collect ages, but those kids will say anyway they are 13 so that doesn’t change the conversation,” Zhu told TechCrunch’s Josh Constine. “We have to make sure the environment is safe.”

Zhu claimed that Musical.ly works in tandem with parents — many of whom, he said, participate in videos and hold “a quite positive view” of the service because it encourages creativity — but its sheer user numbers make it impossible to track and police all users against potential dangers online, particularly when some content is provocative in nature.

“I can’t guarantee [that parents are monitoring all users],” Zhu said. “As far as I know, [users under 13] are being monitored by parents. It’s the same situation as any other social media platform. For the top users, we approach parents using the email supplied in the sign-up process. If we don’t get permission, we will of course delete the account.”

Zhu added that many accounts have been deleted for that reason, although he wasn’t able to confirm exactly how many.

On the plus side of a large community, he pointed out that Musical.ly has tapped into its following to encourage positively with daily challenges, some of which have included anti-bullying initiatives.

“Musical.ly is like a marketing machine,” Zhu, who splits his time between offices in Shanghai and LA, argued. “We can use this marketing power for positive social impact.”

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Away from the user base itself, social is a dog-eat-dog space. Facebook missed ephemeral and it has tried to clone Snapchat many times, with its efforts through Instagram showing promise. The danger of success for Musical.ly is that the big dogs step into its entertainment space.

Zhu said that Musical.ly is working to expand its content platform to allow other forms of expression and to proactively hedge any move that rivals such as Snapchat and Facebook may make.

“We feel worried, that’s the nature of startup,” he said of Musical.ly richly funded competitors. “What can we do about it? We can only make ourselves better.”

Live-streaming is a major component of that expansion, and earlier this year Musical.ly released a standalone streaming service — Live.ly — to go beyond recorded content. There, it is pushing its categories and placing focus on competitions that mimic popular TV series like ‘America’s Got Talent.’ Back in the main Musical.ly app, Zhu said the focus is increasingly on expression and not just lip syncing and dancing, the elements it is best known for.

Videos with “lip-sync and music is reducing over time, [and we] see more videos like comedy, sports and fashion,” Zhu explained. “We are in the process of providing more content formats.”

He expressed his optimism that Musical.ly can expand out of its music pigeon hole and become a destination for general entertainment , despite the demise of Vine, the Twitter-owned short video app that is closing down despite achieving a level of cult appeal.

“The most important asset of a social network isn’t the content but the social graph,” Zhu said. “We did social graph analysis, one thing good about us is that 25 percent of daily active users are content creators. Because [there are] so many creators, they connect with each other and form social graph.”

Article updated to correct an error that suggested Musical.ly has 40 million daily users and that one million new videos are uploaded per day