In digital media, the only sure thing is that metrics will continue to get gamed:
Facebook counts the “view” at the three second mark (whether or not the viewer has even turned on the sound) in the midst of a precipitous decline in retention. At that moment, 90% of people scrolling the page are still ‘watching’ this silent animated GIF. But by 30 seconds, when viewership actually could be claimed, only 20% are watching. 90% of people are being counted, but only 20% of people are actually “viewing” the video.
YouTube, on the other hand, counts views in a logical way…the view is counted at the point at which people seem to actually be engaging with the video and not just immediately clicking away. This is usually around 30 seconds, but of course is different for videos of different lengths.