Mobitv, while "live", has a buffer on it, just as Verizon's version of moble TV has on theirs.
MediaFlo is true moble tv. it's a live tv feed broadcasted using a HD channel, which can be broken down into many other subchannels. There is no bufferning, and it's only available in certain locations at this time. Also, it has nothing to do with AT&T's 3G network.