Our videos are hosted through Amazon, so if you haven’t already, you might try adjusting the resolution on the videos to see if that helps speed things up.
At the bottom right of each video you’ll see the words “HD,” and if you click on that, a little box will pop up so you can change the resolution of the videos. Usually, Vimeo sets it to “auto,” but that doesn’t always capture your internet speed properly, so you can adjust to a lower (or the lowest) setting manually.
The video will still look good, but lowering the res should help speed it up a bit more. You can also press play, then pause the video for a bit, and press play again to allow the video to buffer.