i havent converted movies on g6 or ds before but i have convert movies for psp and other stuff. Its quite slow. You can probably get it to fit in the G6 lite just make the resolution lower cause its not really going to matter. It doesnt compress files but it does get smaller.
it "compresses" movies and also makes them a new format. it compresses by changing the size of the movie to whatever the resolution is for the screen of the DS/GBA.
Average convertors I would say take about 20 minutes or so, not 100% sure as i haven't used any as of yet (but will now that i don't have my DS Lite, only my GBA for a few weeks)
BatchDPG usually takes about half the time of the movie to convert (will obviously be quicker/slower depending on computer specs) so a 90min movie will take 40-50mins to convert.
Try changing some of the settings, like turning the bitrate of the sound down and reducing the frames per second, i got FFVII:AC down to ~300MB when I had it on my M3.
thanks guys, i actually got batch to convert a rm to a gbm. I tried playing it on my gba and it worked barely with no sound, ill try again once i get my ds lite
however, i checked the file size and it said 490mb!, the original is only 44 and the converted was 46