I think that might be the original Ultra patch-- later on a different site added patches for all the Windows games that mostly just double the bullets (much like the transition from SoEW Normal to Hard mode).
I find it interesting that not only does it change bullet types and sometimes entire patterns, but even removes the graze cap, increases the score cap (to 2
31), and makes all the spell bonuses absurdly high.
I've seen it in a few other videos (including
a TAS), but have no idea where to download it. If I recall correctly, the main game has been edited too, just as thoroughly.
Edit: On a related note, the video you linked was definitely played with slowdown.
I've seen a legitimate (as far as I can tell) run of it before though,
here. Actually, there's what appears to be a download link for it in that video's description, so I suppose you could try that...