An anonymous reader quotes a report from Rolling Stone: Verizon, AT&T, Johnson & Johnson and other major companies have pulled advertisements from YouTube after learning they were paired with videos promoting extremism, terrorism and other offensive topics, The New York Times reports. Among the other companies involved are pharmaceutical giant GSK, HSBC, the Royal Bank of Scotland and L'Oreal, amounting to a potential loss of hundreds of millions of dollars to the Google-owned company. The boycott began last week after a Times of London investigation spurred many major European companies to pull their ads from YouTube. American companies swiftly followed, even after Google promised Tuesday to work harder to block ads on "hateful, offensive and derogatory" videos. Like AT&T, most companies are only pulling their ads from YouTube and will continue to place ads on Google's search platforms, which remain the biggest source of revenue for Google's parent company, Alphabet. Still, the tech giant offered up a slew of promises to assuage marketers and ensure them that they were fixing the problems on YouTube. Due to the massive number of videos on YouTube -- about 400 hours of video is posted each minute -- the site primarily uses an automated system to place ads. While there are some failsafes in place to keep advertisements from appearing alongside offensive content, Google's Chief Business Officer Philipp Schindler wrote in a blog post that the company would hire "significant numbers" of employees to review YouTube videos and mark them as inappropriate for ads. He also said Google's latest advancements in artificial intelligence and machine learning will help the company review and flag large swaths of videos.