If you downloaded the first version of the ROTJ BD50 disc, and want to get the new HD menu without downloading another 50 GB (perhaps you have a monthly cap or something like that), i have a way you can download just 200+ MB and convert the original download into the updated one!

i used xdelta to create a binary diff of the two files (http://xdelta.org/).
this is how i created it it:
xdelta3 -9 -S lzma -B 2000000000 -W 16777216 -I 0 -P 16777216 -e -s "Return of the Jedi Despecialized BD50.iso.old" "Return of the Jedi Despecialized BD50.iso" "Return of the Jedi Despecialized BD50.xdelta"

you can find this on most linux repos (and via macports), and get windows binaries here: https://github.com/jmacd/xdelta-gpl/releases/tag/v3.0.11

to apply the diff/delta, you need the original iso (renamed to .old), plus my patch file which you can get here: https://mega.nz/#F!Eo5kDLZA!RN2auJSFvwoTZv9kv7U5oA

xdelta3 -d -s "Return of the Jedi Despecialized BD50.iso.old" "Return of the Jedi Despecialized BD50.xdelta" "Return of the Jedi Despecialized BD50.iso"

this should get you the updated file (sha256sum):
819e30e6ddf616a95e0818dfa86f3fecc0b3014b27cbc4189fac3f08856eb87d Return of the Jedi Despecialized BD50.iso