Last year was a tricky one for YouTube, by its own admission. It faced issues with "brand safety," where big-name ads from companies including Mars, Adidas and Deutsche Bank were running against videos showing violent or other inappropriate content.
Then at the start of 2018, it put a partnership with top content creator Logan Paul on hold, after he posted a video of a suicide victim in Japan.
From February 20, YouTube will start to remove smaller channels that currently run ads, according to a blog post by Paul Muret, its vice-president of display, video and analytics.
At the moment, channels have to reach 10,000 total views to be in YouTube's Partner Program (YPP), but under the new rules they will need to have at least 1,000 subscribers and 4,000 hours of watch time to be eligible to run ads.
YouTube is aiming to prevent those who create undesirable or spam videos to make money from advertising and reward creators who make good content. "While this new approach will affect a significant number of channels eligible to run ads, the creators who will remain part of YPP represent more than 95 percent of YouTube's reach for advertisers," Muret wrote on Tuesday.
Additionally, the site will have staff manually review videos for Google Preferred, which puts YouTube's most popular content into packages for advertisers. Paul's videos were part of Google Preferred and he was one of the video site's most popular creators.
"There's no denying 2017 was a difficult year, with several issues affecting our community and our advertising partners," Muret said. "We are passionate about protecting our users, advertisers and creators and making sure YouTube is not a place that can be co-opted by bad actors."
YouTube is also working with analytics companies Integral Ad Science and DoubleVerify to better report where ads have been placed. "We also know we need to offer advertisers transparency regarding where their ads run," Muret wrote.
The impact of digital advertising is a big issue. Facebook was criticized for its ad measurement techniques in 2017, with a report from the Video Advertising Bureau suggesting that it reached 1.9 million people aged 18 to 34 in Chicago, when only around 800,000 people of that age were reported in census data.