As someone who's part of a team that watches a lot of online screeners, you need to know that the reported view metrics aren't 100% accurate. Each video hosting service is different, but any number of things can happen that can lead to a dropped play event from being logged. Things like a temporary internet connection loss, a service error, or watching a film offline, or starting a video on one device and continuing on another. Vimeo and YouTube may show you a specific number (9,457) but know that it's always +/- a few %.
If it happens once or twice, it may just be chance. If it happens consistently over and over again, then it's safe to suspect foul play.