I've noticed this issue most with Youtube (through both the browser and the Leanback app), but I've noticed it once with Vimeo and once with Navi-X. What happens is the video simply stops playing. Most often I've noticed that the video just didn't load past that point, and I can skip past the point it loaded to get it going again, then return to where I left off. Other times, the whole video has loaded but it stops anyway, and I have to refresh the page and find where I left off to get it going again. I notice this most on long videos. It only happens every 15 minutes or so during the video.