Blast. Of course Comcast doesn't carry those. Will be working so was banking on a friend's DVR saving the day. Don't have any hope that the NBC sports app will have the replay up after the fact either, don't think they've had replays for at least the last 3 games of ours.
I don't know enough about how US TV works, but I have Comcast/Xfinity with an X1 box and I can watch the Live Extra channels. I watched... uhh... Crystal Palace against... somebody on it recently, and it was a pain in the ass to figure out, but it worked great once I got in. Had to go through a bunch of on demand menus and it looked like an old replay, but was actually live.
It might be that your Comcast is different to mine because of your location etc., but I'm pretty confident I can watch us tomorrow on mine. It's not intuitive at all, but it is there.
Of course, AceStream is also easy...