SAN FRANCISCO (AP) — YouTube's year-in-review video is usually a celebration of video creators who upload free clips — sometimes wacky, sometimes personal, sometimes offensive — that the company then sells ads against.

But this time, the video-sharing network provoked a backlash from creators and viewers with "Rewind 2018," which sidelined many prominent YouTubers in favor of mainstream celebrities and an inclusive, feel-good message.

The snubbed YouTubers and their fans quickly retaliated with a passive-aggressive but potent protest. Within a week, "Rewind 2018 " was the most unpopular video on the service, now with more than 15 million dislikes. So intense was the dissent that YouTube CEO Susan Wojcicki sort-of apologized and reached out directly to at least one neglected YouTuber.

The outcry highlights the challenges YouTube faces as it tries to navigate the tension between creators who make the videos, some of them controversial, and the advertisers who fuel profits.

YouTube is an increasingly important business for parent company Google. Although Google doesn't break out YouTube revenue, the research firm eMarketer estimates that YouTube ad revenue grew to $9.5 billion in 2018, up 22 percent from the year before. YouTube makes some of its own videos, but relies heavily on outsiders for the vast majority.

As YouTube grows, it's easier for YouTubers to feel slighted by YouTube's attentiveness to advertisers. Some saw "Rewind 2018" as an effort by YouTube to present a sanitized version of itself, said Luke Majoinen, who runs the entertainment YouTube channel Joinen, which has more than 200,000 subscribers. "It's pretty much an ad for YouTube."

Video creators disillusioned with YouTube don't have many alternatives. Although there are other options — Snapchat, and an increasingly competitive Instagram — it's still the first place viewers turn to watch videos. And it's the most viable way to make money, Majoinen said.

Creators who have enough subscribers to their video channels — usually more than 1,000 — can apply to get paid a sliding rate when enough viewers watch ads that run with their videos.

In her quarterly blog post to YouTubers, Wojcicki acknowledged that her kids found the Rewind video "cringey."

"We hear you that it didn't accurately show the year's key moments, nor did it reflect the YouTube you know," she narrated in an accompanying video as thumbs-down icons popped up on the screen. "We'll do better to tell our story in 2019."

In particular, the Rewind video appeared to steer clear of some popular but controversial video creators. It featured more than a dozen celebrities who used YouTube to launch their fame, as well as mainstream celebs such as Will Smith and Trevor Noah.

But it excluded one of the top YouTube stars, Felix Kjellberg. The Swedish YouTuber who goes by PewDiePie has 86 million followers. YouTube has distanced itself from him after he made jokes criticized as anti-Semitic and posted Nazi imagery in his videos. YouTube also excluded Logan Paul, who made an infamous video in Japan's Aokigahara forest, sometimes called the "suicide forest," which appeared to show a dead body hanging from a tree and Paul giggling and joking about it.

Kjellberg and Paul have both apologized for offensive videos. And despite the transgressions, their audiences stayed strong. The pair still hold power on a service where so much is determined by subscriber loyalty.

Many YouTubers responded to Rewind by posting reaction videos expressing their disappointment. Kjellberg made his own version of Rewind, which heavily featured what many thought YouTube's video was missing - himself. (That, and memes.) It garnered more than 7 million likes.

Companies know advertising on YouTube can be risky, but it also attracts an audience that can be otherwise hard to reach, eMarketer principal analyst Paul Verna said.

Advertisers flexed their muscles in early 2017 and began boycotting the site until it could prevent their ads from appearing next to extremist clips promoting hate and violence.

The boycott was short lived, but smaller boycotts have popped up since, including one over the past week when AT&T, Nestle and Epic Games suspended ads on YouTube while the company worked to quell inappropriate comments that sexualized children on otherwise innocuous videos.

YouTube allows advertisers to choose topics and demographics to target with their ads. But some companies want to see stronger protections against inappropriate videos to assure their ads appear next to safe videos.

YouTube has taken action to protect advertisers, but creators now complain that YouTube's countermeasures results in some of their videos being improperly "demonetized," or classified as not suitable for ads — which means they don't earn money. YouTube didn't respond to a request for comment on demonetization.

YouTube's Wojcicki, however, did respond directly to a PewDiePie video on the subject. In a comment, she pointed creators to an official video explaining demonetization and noting that YouTube still promotes demonetized videos through its recommendation engine.

Majoinen and other creators say they're standing behind YouTube.

"I'm optimistic they'll continue to work on blind spots," said Marques Brownlee, who appeared in the Rewind video and runs a tech review YouTube channel that has 7.8 million followers. His own reaction video to Rewind also noted its advertiser-friendliness.

There is good news for one artist in all this — Justin Bieber no longer has the most disliked video, a title he previously held for the music video of his song "Baby."

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