I've talked to Sonic's Tech Support about this whole Seamless Branching issue and he told me the guy who built and programed Scenarist (apparently only one programmer that did it) would have to completely rewrite the Interleaved Muxing Engine. But because Scenarist can author by VOBID you can make a type of seamless branch and achieve the same effect of a "real" seamless branch. and he went on to say ..."because of that, there really is no point to write that code." According to him, its a very hard task to do and not many people would use it in a DVD. He also said that (non HD Version of) Scenarist will most likely never support "true" seamless branching. Perhaps the HD Version of Scenarist will support it, I don't know. But that was straight from the Senior Tech guy's mouth.