Since its foundation in 2005, YouTube, which is considered to be the largest video-sharing site, has undergone substantial changes. Over the last decade, the platform developed into a leading marketing tool used for product promotion by social media influencers. Past research indicates that these influencers are regarded as opinion leaders and cooperate with brands to market products on YouTube through electronic-word-of-mouth mechanisms. However, surprisingly little is known about the magnitude of this phenomenon. In our paper, we make a first attempt to quantify product promotion and use an original dataset of 139,475 videos created by German YouTube channels between 2009 and 2017. Applying methods for automated content analysis, we find that YouTube users indeed are confronted with an ever-growing share of product promotion, particularly in the beauty and fashion sector. Our findings fuel concerns regarding the social and economic impact of influencers, especially on younger target groups.