That used to happen to me all the time when I was with Cox Communications. I would be having trouble streaming Netflix/Hulu on a 50mbps connection. I'd call them up, they had me do a speed test, which would be great, Netflix would start streaming, so I'm done with tech support. Fifteen minutes later, Netflix starts buffering again.
I did find that if I ran the speed test on their site, which was a flash based one, that the speed would go up to. They must have their system tuned to recognise when that speed test is run, and increase your allotted speed. So what I started doing is keeping their website up on the laptop when I watch Netflix. Set a timer for 12 minutes, I'd run the speed test on the Cox website and my speed would be boosted. No more buffering, just the small interruption of the timer and looking over to start the speed test again.
