My guess is that they are being blocked by the proxy. The only other thing that I can think of is to make sure you have the latest version of flash player installed. If it's not Flash or the proxy, then there is likely a setting on your computer or browser that may be causing the issue, but I can't say for sure. I don't want to tell you to change any of those settings, especially if it's a work computer.
An alternative is that you can go to our youtube channel and view the videos there since youtube isn't blocked: www.youtube.com/user/sparkpeople
Hope that helps!
"You may have a fresh start any moment you choose, for this thing that we call "failure" is not the falling down but the staying down." Mary Pickford
"No matter how slow you go, you are still lapping everybody on the couch."