m2vrequantiser can be used by mytharchive to create DVDs and .iso's but it's apparently not available in 12.04 universe repository.
Is there some way to get it for 12.04.1?
I'm having the same problem. I fixed it by installing it manually for now, until the dependency is back in apt.
I also see two more bugs with the burn to dvd flow of mytharchive. See https://bugs.launchpad.net/mythbuntu/+bug/1131280