You need to decimate the framesize - try decreasing by a factor of 2. This may become unplayable in some standalones. You can also encode the audio to MPEG layer 2 to squeeze on more video, but again this may become unplayable.
Is you source 4:3 or letterboxed? You need to play around with the arrange settings in TMPGenc. Take a look at this
http://www.marcpeters.co.uk/convert-4-3-to-16-9.html.