I've noticed over the last few months that YouTube performance is really bad on cable for me. Only some videos will download as fast or faster than they play (low quality videos). Most download at perhaps 70% play speed, which means constant buffering, or pausing for many minutes at the start. Is this the case for others on cable, or even TelstraClear ADSL?
Here's an example video: http://www.youtube.com/watch?v=F1jmhbw3JHw
If I let it run in non-HD, it plays for 2 seconds, then buffers for 5 seconds (repeat). For HD, it's 2 and 7 respectively.