I think Comcast is doing the same thing here in Colorado. Lately, I've been seeing quality drop in videos where it shouldn't. Running speed tests or downloading from newsgroups I'm hitting 60mbps.
You'll be happy to know that Comcast's Denver ibone switching/routing has been over capacity for many months at this point...Same goes for their Oregon switches (which service SV and the PNW seaboard)
http://ispspeedindex.netflix.com/results/usa/graph Looking at comcast over the last two months looks like there is some data to confirm your notes about their backbone having issues. They are on a steady decline.
Same here for Comcast in Seattle. From 6-8pm I can't stream youtube on anything more than 360p or it buffers constantly.
Other video streaming services seem to stream fine (Netflix, Hulu, Amazon Instant Video) and speedtest.net reports 56Mbps down, it's just youtube that suffers.
Ditto here re Comcast, but in Mountain View. I am a stone throw away from YouTube HQ and still get bad performance. Tried the 8.8.8.8 DNS and not much different. Comcast is definitely squeezing the pipes!
