That happens with me sometimes, as well. What I do is keep playing the choppy video until it finishes, and then when I replay it, it works fine. This usually happens when my internet connection slows down, and, as a result, it takes a while for the video to download/buffer/stream.
I may have misunderstood you. Do you have a problem viewing the downloads, or the teasers for 1-on-1 on the website?
If you have a problem with viewing the downloads, make sure you have the latest version of Quicktime player, http://www.apple.com/quicktime/, and if that doesn't work try to download the free VLC player, from http://www.videolan.org/vlc/, and play the file with that.