I've had this problem for weeks and am about to give up. Stream, Progressive, HTML 5 playing is all very poor. Videos stop and start (buffering, presumably) almost non-stop. Play ten seconds or so, then hang for half a minute or more while loading, before playing more.
Youtube versions work fine.
GB channel on Roku takes a while, then loads just enough to watch between one and three seconds of video. Then it goes back to the loading screen, where it takes so long for the loading bar to fill up that I give up (after several minutes, at least).
Netflix, Hulu, Amazon, TWiT, MOG, PLEX, TED, Machinima, REV3, and other channels all work fine.
Downloads via GB are unacceptably slow. A 1.08gb video will download between 60KBps and 80KBps, meaning a 1.08gb file (such as one Endurance Run episode) will take 4-5hrs. This happens on a 27/10mbps Comcast Business connection. This happens on Win7 and OSX. This happens on Chrome, Safari, Firefox, and MSIE. This also happens via VPN, routing through Dallas or LA.
This problem is not common anywhere else.
This suggests it isn't an issue with browser, operating system, machine, available bandwidth, or (unless they're somehow performing some deep-packet VPN-encryption-busting inspection) ISP.