This was recently discussed in the backroom, I believe. Someone tipped us off that the FAQ for ESPN3 had recently changed (August 27). Go to the link below and start reading down from there.
Interpretation: ESPN got tired of losing standard cable customers to people who were getting the content off ESPN3 (through their Internet provider) that was also showing on ESPN, including college football games. Therefore, between the hours of 6 p.m. and midnight, local time (your time zone), they will not allow you to watch content on ESPN3 which is also live on ESPN. That's why the West Coast guys could watch the game, because it was not in their prime time slot. If the game was in LA, the West Coast would have been blacked out as well (but not Hawaii/Alaska). They pulled the rug out from under those of us who expected ESPN3 to show live prime-time ESPN/ESPN2 content, since they had been doing that up until late August. The prime-time stuff is only available to WatchESPN customers (read: standard cable subscribers).
You *will* be able to see the replays and there are events that will be live in the evening on ESPN3, but not if they are on ESPN or ESPN2. As someone else noted, if the BC-ND game later this year is an ESPN game, it will be blacked out in primetime on ESPN3.
Read all of the FAQ.
(In my area, TWC does not offer ESPN3 to their Internet-only customers, but AT&T U-Verse does.)
I have no idea how they arbitrarily chose to do that, but it's really annoying.