I was watching a Sermon form my Church on vimeo last night & it kept buffering several times. I went into settings>general & my wifi strengh we 4 out of 5 bars. Everything else seems to work fine.
could have been a network bottle-neck anywhere between the server the video is hosted on and your device that could be gone now... in these situations, you can try again later - or download the video and store locally if possible for later viewing.