I see you've taken some creative liberties with the character placements but I won't fault you for those. One thing to note, is that in the original Reimu is a bit closer to Sanae and rendered behind her (it's supposed to create the illusion of them cuddling, I hope one can guess from the screenshot just how close friends they're supposed to be), whereas your video has them… h-hand-h-holding. T-that's l-lewd.
The font choices seem somewhat weird and arbitrary. It's one font to indicate who's speaking, plus one font per speaker. If you're doing different fonts per speaker, I'd also do it for the speaker bubble, but use a thicker weight. E.g. write Sanae in Sanae's curly font, but with "bold" added to the attributes. This might be a bit difficult with Alice, whose normal font is already bold to begin with but I'm sure you'll find something.
At around 7 minutes, "Marisa" and "Alice" overlap in the speaker bubble. That's probably an error ;)
I don't think I've seen anything else, but I've only given it one or two watches – significantly less than I did for my own source code after which I still found typos.
As far as making a video about this game and publishing it on platforms such as YouTube is concerned, you are (mostly) free to do as you please, but bear in mind that the source code itself as well as the assets prohibit commercial reuse. In other words, try your best to make Youtube put no ads onto the video (this is not to imply that there are currently ads placed on it, just to remind you to not let YouTube place any on them). I'd also welcome it if your video title reflected that it was a fan animation, but that's no hard requirement.
TL;DR:
- Try matching up your fonts better
- Fix the overlapping names at ~7min
- Make sure the video stays ad-free
As far as starting a new comment chain to reach more people is concerned: Feel free to do so, but make sure to keep it civil (I trust you to do the right thing).