>imported 8 mm video that had been recorded onto mini-dv tape
That is a Standard Definition video... so "of course" a BluRay will look no better than a DVD... you may "up rez" your SD video into "faux" HD video, but you still started from a Standard Def source
Now... obtain some HiDef AVCHD video
Export a "down rezzed" DVD file and create a DVD... and and then an actual HD file and create a BluRay... that will be your true test