I tried most of the tips here, here and here (I didn’t clean out the registry). I also checked my download speed at speedtest.net and it was over 20Mbps. I recall YouTube videos loading much faster in the past. Now I can’t get through a video without waiting for it to start and it stopping several times waiting for the video to catch up to the buffering.
I’m sorry I don’t have an answer, but I want to note that the same thing is happening for me. I have a LIGHTNING fast internet connection, but anything 480p and above takes a while; 1080p isn’t worth the wait.
Someone I know said Youtube throttles, so maybe it’s because I’m viewing when everyone else is.
If it’s still continuing to load, but just taking longer, then its likely your connection. Try Speedbit Video Accelerator. I’ve recommended it in the past, and, so far, every who has used it says it really helps.
Now whether the connection problem is with your PC, connections, or ISP, I don’t know. I’d definitely try some different cables and do some sort of antimalware scan, especially if other video sites also mess up. Malware can steal bandwidth when it “phones home.”
If it’s just YouTube, though, Speedbit should be sufficient.