caps with the Hauppauge PVR 2 on Youtube are very choppy

I have uploaded some video test on Youtube with the PVR2 and they play very choppy. On minimized viewer it seems to run at like 20 fps, but if I play full screen it run almost normally at 30 fps. I don't understand why it does that. I have uploaded many h.264 ecoded mp4 before and it never did that. I thought first it was the bitrate was too high, but even at 10Mbps it still cause frame drops. And I have uploaded many higher rate bitrate mp4 before and it was never an apparent issue.

Anyone has some idea what's the cause?

EDIT- NEVERMIND, it appear that Youtube is the problem. All my previous video is choppy as well.

How I can delete this post?