I have not actually played the original version. So don't really know.
Is the DX version really harder? In the change log it says the DX version has music in game, better 2 player mode and more enemies. It says nothing about modified difficulty.
There is another video on Youtube. He plays the original version. He did not get these big sprites running across the screen. Is this because he played the game on easy or is these sprites just in the DX version? I'm too lazy to load the game and check right now.