Debilitating issue I'm having with videos

This has been happening for a while now, not during every browsing session but I'd say up to half. Videos stop and skip to the end at random points in the middle of watching. When I try to replay they either won't (error message) or they skip to the end at the same point over and over again. This seems to be connected with receiving "playback is unavailable" (or something like that) messages from Vimeo. It fucking sucks. Most of my time spent on NS is at school - running adblock and ultrasurf - so I'm not sure if its just an issue I face at school because I dont have experience with the problem anywhere else. I'm on Chrome. Doug, help me!