Vietnam Airlines fly MEL - SGN -HAN 3,4 or 5 times a week (I can't remember), but they are always 90% full or more. They fly B777 and I don't know what IFE is included, but I guess you could always check their website.
I haven't checked fares, but I would say to go direct with VN would only be $100-200 more, than the slog with JQ. With the QF group and fuel surcharges VN may even be cheaper. And also quicker.
Even on staff travel if I have to go through SYD to get a QF flight, I'll most likely go with the carrier who flys direct ex MEL. I do like Jcls when possible, but on staff travel it is such a hassle to go somewhere through SYD. Coming home through SYD is a lot easier than departing.