Thanks for the update. The speed of the Wi-Fi in the coffee shop will depend on many factors. What is the speed of their connection to the Internet? How many people are sharing the Wi-Fi? Is it 802.11b or 802.11g? Do they have a microwave operating nearby? That will often interfere. Are there additional Wi-Fi networks nearby? That can interfere as well. It's possible that it was their network that's causing your trouble. But, to rule that out, did you try using Safari instead? You might make sure you have an up-to-date version of the Flash player which you can get at
http://www.adobe.com
I have
Clearwire at home, it's basically like wireless DSL. It's not as fast as cable Internet access, but it is portable. I only mentioned it because it would indicate that you don't need cable speed to watch the videos without buffering.
-Doug