Last time this was discussed on YC: [1] Except that time it was the "Thor" codec.
MPEG-2 is effectively out of patent now for almost all uses. Here's MPEG-LA's patent list.[2] The one remaining unexpired patent [3] only applies to error correction for pay-per-view satellite broadcasts.
[1] https://news.ycombinator.com/item?id=10042469 [2] http://www.mpegla.com/main/programs/M2/Documents/m2-att1.pdf [3] https://www.google.com/patents/US7334248