BURN still works in Sierra..surprisingly (10.12.6).. But i gave up on this as well. not by the "temp" mpg it creates in folder, I didn't have an issue with that, but by the limits that BURN could support, as there was too many problems with getting ac3 audio over. Even Perian installed didn't fix it.
I put up with that for a while, but then it got too hard needing to install other things to support it.
For "Data" discs, it works perfect though.
Toast always worked in these types of cases, but the slowest just drew me away from that..
encoding small videos with toast is fine, but never 2 hour movie. Took about an hour just to encode. on the "best quality setting"