Social app Musical.ly continues to grow at a clip, with CEO Alex Zhu claiming yesterday that it now has 40 million daily active users uploading a million new videos a day. More than 130 million people have so far registered for the app. Zhu said that Musical.ly is trying to move beyond music: “lip-sync and music is reducing over time, [and we] see more videos like comedy, sports and fashion,” he told the TechCrunch Disrupt conference. “We are in the process of providing more content formats.” That won’t remove the pressure on Musical.ly to sign licensing deals with music rightsholders, although it already has an agreement with WMG in the bag. Musical.ly’s key challenge is clearly highlighted in another part of TechCrunch’s writeup of Zhu’s appearance: about the many children who are using its app. As it signs more licensing deals, the company will have to make more money: but whether it decides to sell content or features to users or implement advertising, a big audience of under-13s is a regulatory problem – in the US alone, Musical.ly will need to find a way of making money that doesn’t fall foul of the stringent Children’s Online Privacy Protection Act (COPPA) legislation.