Originally Posted by Gerald LaFrance YouTube isn't uploading videos to their ISP as you're downloading them. The typical consumer upload speed of 1Mbps is irrelevant for YouTube.
You're right in that my SpeedTest and ISP claims of 25 Mbps don't necessarily correspond to YouTube download rates. But my upload rate is irrelevant for watching videos, I need better downstream capability from my ISP and perhaps from YouTube's content-distribution network.