Following is a transcript of the video.

Narrator: TikTok is one of the most popular apps in the world. It's been downloaded over a billion times in the two years that it's been around. And it has produced countless memes. Even Mark Zuckerberg sees TikTok as a threat. But its rise hasn't been seamless. US senators have criticized TikTok for censorship, privacy, and child safety. So, what's going on with TikTok?

Shona Ghosh: TikTok has a bit of a complicated history. It's owned by a parent company called ByteDance, which is from China. ByteDance is one of the most valuable startups in the world. It's thought to be worth about $75 billion, which is massive. There are definitely concerns in the US about TikTok being a Chinese app that has become hugely popular in America, and, frankly, that's probably a mix of Americans being worried that their own homegrown companies, like Facebook, Google, etc., being outdone by a Chinese firm, but secondarily, you know, this concern feeds into the wider backdrop of the US-China trade war.

Narrator: TikTok lets users easily share short, funny clips. That means things can go viral quickly, and that virality has helped TikTok grow.

Ghosh: So, TikTok has about 1 billion monthly active users, which is about the same as Instagram, and TikTok, in terms of downloads, is absolutely besting the competition. It's beaten Instagram, Snapchat, Facebook. That's not to say in total TikTok is more popular than these apps; it's to say that it's growing really quickly. Part of the reason is because TikTok is relatively new, it's only been around properly for one or two years, and so there's a kind of natural newness bias there. You know, the billions of people who were already going to download Instagram, WhatsApp, Facebook, they'll have probably already downloaded those apps, whereas TikTok, being new, the number of sort of growing installs we're seeing is about people downloading that app for the first time. It's all about these short video clips, most of which are kind of snappy and funny and involve someone kind of dancing and lip-synching to music. These things go viral really quickly, and it's also really easy to share what you've made on TikTok to other platforms.

Narrator: TikTok is sort of a natural successor to the once popular Vine. But there's a lot that sets TikTok apart from its current competition.

Ghosh: One of the big criticisms of, let's say, Instagram is that everything feels very artificial on Instagram. And it's not really an app about spontaneity or about posting spontaneously. You know, it makes people feel kind of pressured to post the perfect picture, by extension show that they're living the perfect life. Where TikTok comes in is it's a much more spontaneous, instantaneous, it's all about short clips, it's all about kind of goofing around. It's not about looking great or perfect. This is why it's so popular; people feel that they can just post immediately and they don't have to think too hard about the content. I'm sure many of the more popular TikTok-ers do think very hard about what they post, but it feels much more instant than Instagram. It's pretty clear just from who's posting on TikTok that the user base is younger than your average, certainly younger than the kinds of people who use Facebook, probably younger than the 20- to 30-year-olds who are using Instagram.

Narrator: Having so many young users is a clear sign of TikTok's popularity. But it's also gotten TikTok into trouble. In February, the company had to pay a $5.7 million fine after the Federal Trade Commission accused Musical.ly of violating US child-privacy laws. TikTok now requires users to verify their age in the app, although the age of TikTok's users isn't the only concern people have.

Ghosh: There are definitely concerns in the US about TikTok being a Chinese app. And TikTok itself isn't really a Chinese app, per se; it was born out of an acquisition called Musical.ly, which was popular in the US and the West, and ByteDance actually bought that in 2017 and reskinned that to become what we now know as TikTok. But there's actually a sort of separate version of TikTok that is available inside China, but that's called Douyin, and that's slightly different. Recently, Republican Sen. Marco Rubio called for a committee investigation into TikTok over whether it should ever have been allowed to buy Musical.ly, which is not a Chinese company, and then sort of turn it into TikTok. Whether that investigation actually happens I think remains to be seen, and sort of dependent on the US political environment. Something to remember is that there's a much larger culture of fear, especially in the US, about China and Chinese companies. There's still some criticism that TikTok, being owned by a Chinese company, might succumb to some pressure by the Chinese government either to hand over data on its users to the Chinese government or to kind of censor topics that, you know, would be fine in the West and in Europe but not sort of OK inside China. We're not actually really conclusively sure that China does have an influence. Recently, The Guardian got hold of some moderation guidelines that show that certainly, the parent company, ByteDance, was thinking about, you know, censoring videos that might be, that might cause offense to the Chinese government and other regimes. It wasn't just talking about moderating content offensive to China; it was talking about generally political content, too. So we do know that there are some thoughts inside the company about censorship, but what we don't really know is, you know, practically how this filters through. There isn't an awful lot of proof that TikTok does take guidance from China in terms of what users can and can't post. So far, the company has been quite good about explaining to journalists, or at least giving statements to journalists, about how it works, but it's definitely gonna continue batting off those concerns. There's really no easy answer to how TikTok can balance free speech with Chinese censorship. It's gonna have to make calls on a case-by-case basis; it's probably gonna have to be really transparent about how and why it makes decisions, but overall, other companies are really struggling with, you know, appeasing China and maintaining the balance with free speech, including American companies, so, Apple has run into issues over banning an app related to the Hong Kong protests, and there's criticism that Apple has really kowtowed to China over that decision. And so, you know, even American companies are really struggling with keeping Chinese consumers and China's government happy while, you know, maintaining that balance with free speech.

Narrator: Despite its rapid growth, TikTok hasn't developed a strong source of revenue. TikTok has a lot of venture-capital backing, but it will have to generate a profit eventually, which could mean ads or paywalled features. But if TikTok wants to continue growing at its current rate, it's going to have to find a way to gain the public's trust outside of China.