Streaming streaming services are traditionally large TV advertisers attracting viewers, but when connecting with fans, they are increasingly online, helping marketers target viewers on YouTube and Facebook. Top shows are one of the most popular content on YouTube, and while official channels generate a lot of traffic, fan content generates billions of views, making YouTube a potential venue for advertisers to connect with fans.

Zefr found in a recent TV 3.0 report that 77 percent of Netflix-related content is fan-driven, with more than 81,000 fan channels on YouTube and 10 official channels. These fan channels have 4.7 billion views and 46.8 million fan interactions, compared with 1.2 billion views and 10.9 million interactions on the official website.

Rich Raddon, co-chief executive of Zefr, said: "Research shows that we've known for a long time that when the fan community watching OTT content wants to expand the conversation, they go to YouTube. The trailer for the second season of Netflix's Stranger Things quickly attracted about 9 million views on YouTube.

"You're going to see a lot of ads for Netflix shows on YouTube, which is a real fertile ground because there's all the activity going on in these communities." YouTube is a great place because we know that young streaming viewers are very tech-savavty. This is a great place to tap into new subscribers or content new subscribers. "

The hottest show on YouTube is HBO's Game of Thrones. This was followed by the older HBO show Sex and the City.

The rest of the top 10 are Stranger Things, Orange is the New Black, Last Week Tonight, Defenders of Miracles, House of Cards To Contain Your Enthusiasm, Narcos. Advertisers can buy ads on HBO or Netflix, but still have a chance to stay close to the hit content on YouTube.

If you're a Netflix marketer, if you're a marketer for Hulu or Amazon Prime, and you're releasing 80 feature films you know in a year, how do you properly target audience content that interests you? Film studios and television networks have been using entertainment-related content on YouTube to promote movies and TV shows. 

But marketers of other products also have a chance.

Advertisers accustomed to buying specific content can take advantage of the size of YouTube, "where there's a lot of content on YouTube that might not be made by Netflix or HBO, and it's brand-safe, and that's part of our core business at Zefr," said Byrne, a former google advertising sales president.

The advertising business is different from any other third-party technology on the YouTube platform and is different, curated videos one by one. Then, adjust the video to brand-related content, and then sell the packages to advertisers, which in recent years is sure to be a favorite of advertisers.