I also put a post on the xbmc.org forum about .mt2 files playing in XBMC and found out some good info. If you create a file called Advancedsettings.xml and save it to the /user/library/Application Support/XMBC/UserData directory you can get XBMC to include .m2t into its accepted file formats. Here is what you put in Advancedsettings.xml:
Enter XBMC and play your hi def recorded content! Now if I can only find a way to contact someone from Verizon to ask why CBS and ABC are flagged Copy Once!