Alphabet's (GOOG -1.55%) (GOOGL -1.58%) YouTube is the world's biggest video streaming platform, with over one billion users in more than 88 countries. But one major country it can't reach is China, where it's been blocked since 2009.

That ban left the Chinese market wide open for domestic streaming video platforms to flourish. IHS Markit estimates that the entire Chinese online video market could grow from about 22 billion yuan ($3.5 billion) in 2015 to 96.2 billion ($15.2 billion) yuan by 2020.

Three young women watch TV.

Image source: Getty Images.

Therefore, growth-oriented investors should familiarize themselves with China's three biggest online video platforms -- Tencent (TCEHY -2.78%) Video, Baidu's (BIDU -2.82%) iQiyi, and Alibaba's (BABA -1.71%) Youku Tudou.

Tencent Video

In 2011, Tencent launched Tencent Video as an expansion of its live video streaming platform Tencent QQLive. In addition to letting users upload videos, Tencent developed original content and secured distribution partnerships with six British content providers -- BBC Worldwide, ITV Studios, Fremantle Media, All3Media International, and Endemol UK -- to become the largest provider of British video content in China. It also secured HBO shows and NBA games for its viewers.

Thanks to its massive social media presence -- which includes 980 million monthly active users (MAUs) on its WeChat mobile messaging app, 653 million MAUs on the older QQ messaging platform, and 568 million MAUs on its Qzone social network -- Tencent Video flourished.

Tencent Video had 457 million MAUs as of last August according to QuestMobile and Jefferies, making it one of the top online streaming platforms in China. In November, Tencent revealed that the platform also had 43 million subscribers who paid for premium content.

Baidu's iQiyi

Baidu and Providence Equity Partners launched iQiyi in 2010. Baidu bought out Providence's stake two years later, then secured major content licensing deals with Lions Gate, Paramount, and even Netflix. It also acquired the rights to a large number of South Korean films, and partnered with Japan's Fuji TV for the production of online dramas. iQiyi has also been partnered with Xiaomi -- which invested $300 million in the company in 2014 -- in the development of new streaming technologies.

iQiyi's mobile app.

iQiyi's mobile app. Image source: Google Play.

Baidu controls over 70% of China's online search market, and its sprawling ecosystem of cloud services tethers users to iQiyi. Last August, QuestMobile and Jefferies claimed that iQiyi trailed slightly behind Tencent Video with about 442 million MAUs. But at the end of 2017, Baidu claimed that it had 481 million MAUs, so it remains in a neck and neck race with Tencent Video.

In June 2016, iQiyi disclosed that it had 20 million paid subscribers, up from just five million a year earlier. iQiyi didn't update that figure in 2017, but it could now be comparable to Tencent Video's subscriber base. Multiple reports also indicate that Baidu might spin off iQiyi in an IPO later this year at a valuation of up to $10 billion.

Alibaba's Youku Tudou

Streaming video sites Youku and Tudou merged in 2012 to become Youku Tudou, which was then acquired by Alibaba in late 2015. Youku Tudou grew rapidly under Alibaba, but remains in third place with 325 million MAUs as of last August according to QuestMobile and Jefferies.

Unlike Tencent and Baidu's video platforms, which were extended from their core ecosystems, Youku Tudou wasn't heavily connected to Alibaba's core e-commerce platforms. As a smaller platform, it also attracted fewer distribution partnerships than Tencent Video and iQiyi. As a result, viewers and advertisers often gravitated toward those larger platforms.

Nonetheless, Youku still attracts paying subscribers. In Dec. 2016, it revealed that it had reached 30 million paid subscribers. The company notably added seven million subscribers during a single campaign -- jointly run with Alibaba's payment arm Alipay -- during the Chinese Spring Festival holiday. However, Youku hasn't updated that figure since then, so it's unclear if it's still keeping up with Tencent Video and iQiyi.

Crawling toward profitability

A key thing to remember is that none of these platforms are profitable. But looking ahead, JP Morgan expects China's online video industry to break even by 2019 as the big three platforms convert more free viewers into paid subscribers.

Therefore, these platforms might seem like money pits today, but they could evolve into major sources of revenue for their parent companies over the next few years.