ROM is still a ROM, whether it contains a full game, being a demo or even a distribution-event ROM.
So my opinion says if you talk about downloading, or telling someone to give you and/or giving any download links might lead you to the chopping board. Ouch!
The game-contains itself was free to the public during it was distributed as demo, but the ROM itself is not free and it belongs to the rightful owners that created them. Hope that helps you!