Wi-Fi in Virgin America planes

I am traveling from NYC to San Francisco right now and I wanted to test the Wi-Fi service that Virgin offers on its planes. My idea is to stream a movie - Red Rock starring Nicholas Cage -  from Netflix that I have been wanting to watch for some time now on my laptop. Everything started out hunky dory as we hovered over JFK and I actually got to watch about 15 minutes of the movie at regular speeds. But after a while, the speed started to dive. I had just finished telling a steward that the speeds were good enough for me to stream movies. That jinxed it I guess. I am going around the plane and seeing that plenty of people are on their lap tops. I can bet that a significant portion of them are accessing the Internet through the onboard Wi-Fi service. The onboard Wi-Fi service, called GoGo, costs $12.50 and hopefully will go down as the technology matures. I wonder if there just isnt enough bandwidth for all of us to access the Wi-Fi or its just that the W-Fi is faster when passing over cities and drops as we fly over unpopulated areas. But I believe the days are not far off when steady Internet speeds onboard a plane are a reality.