1. Using YT as a proxy for overall attention. There are so many variables here at work, it's hard to begin to start why this number isn't a perfect science.
2. Advertising isn't a straight line number of attention to sales (even though most geeks in the FB era seem to think so). There are many of factors at play here (branding, image, communication, loyalty, engagement etc) and many are immeasurable.
Believe it or not, effectiveness (and therefore "waste") of ad campaigns are not just how many eyeballs see the ad. I reckon most CMO's wouldn't take this type of napkin math very seriously.
Note - I understand this type of content is for inbound marketing for Embedly, so this is probably quite effective. I'm personally pedantic about the data science behind it so others don't feel betrayed by it.