As ironic as it sounds, YouTube creates a community full of inattention and distraction. Ads and TV shows historically aim to keep you intrigued and focused, but YouTube does not need undivided attention to succeed. In fact, undivided attention helps it to thrive. Watching multiple videos for 30 seconds at a time is more favorable for YouTube than watching one video for 5 minutes. Before you know it, you will have seen more unwanted ads in that 5 minute span than any television show could've delivered to you. Thus, YouTube wins in popularity and profitability and you win in driving, controlling, and ultimately enhancing your already inattentive nature.
Additionally, corporations have found a way to turn YouTube into their own advertisements. Companies find popular people who make videos and pay them to continue to make videos which they turn into ads. They design these videos to look like "normal" YouTube videos and then incorporate their product. So in addition to the short ads at the beginning of many videos, the videos themselves have become ads. Product placement is nothing new, but in a world where we watch hundreds of videos back to back, using this method allows corporations to reach a much broader audience more efficiently and in many cases for much less than in traditional media format.