It seems that I've started an apples/oranges comparison without meaning to. My apologies. Here's my fix:

I neglected to mention why the files were much larger. Each image in the film is far larger (up to 6x the number of uint8 RGB buckets in the image matrix) than SD, so there is a LOT more info to write to the disc. That's why it's such a disc hog, limiting what you can write to a DVD disc. As for bit-rates, the data rate vs. rotational velocity ratios of BD and DVD are proportional, meaning that in theory, a DVD burner is capable of burning a BD movie, albeit truncated because of the small size of the disc. And since Blu-Ray players accept the archaic MPEG-2 codec, BD media can actually be copied to DVD media using the correct software, without changing compression codecs.

It just won't be the full length (or anywhere close to it). Of course, it will still have to be played in a BD player, and you might have DRM hoops to jump through, but it's not impossible.

Oh yeah, and it takes a LONG time to burn a disc with this method. Almost-Not-Worth-It long. But if you're desperate, and have a small BR file, go for it.

And as for the standard MPEG-2, may it die quickly, with H.264 dancing on its ashes.