I've had FIOS for a week, and been unable to watch Youtube videos. They barely buffer, if they buffer at all. Youtube worked fine over my previous ISP's connection, which was a tenth of my current speeds. This is the case on all different machines in my home, including two different desktops and two different laptops. I have tried both wireless and wired connections. Even at the same time that Youtube fails to buffer, I can get HD streams from Netflix, Amazon, or any other similar source. There is plenty of bandwith available.
I found some advice here: http://forums.verizon.com/t5/FiOS-Internet/having-Youtube-probs-with-Fios-I-have-an-official-VZ-answer/td-p/538809 and followed the steps but it has made no impact.
Any advice would be great. I work in IT, so lay it on me in as complicated terms as you'd like.