Can’t, this was the only copy ever made - to the best of my knowledge they received two guitars made by Schecter as their signatures up to their spec, one was Blackjack ATX C-8 and the other was V-8 - the one on the vid. Recogniseable by the specific inlay on 12th fret (did I ever mention I am absolutely obsessed by this band? XD). At least this is what I’ve read from a thread former guitarist created on some Polish guitar forum, I’d share the link but… it’s all in polish.
This is what they looked like:


On a side note, I absolutely adore that white V-8, such a beauty.
I mean, it is not impossible there were more, but unlikely.
I’d rather lean on the guitar being de-tuned every few songs, this can be verified though - I can’t remember if they played any older songs right before/after the newest one that were using 8-strings, but I don’t think so. Would need to check YT if there is such instance. I can easily imagine them writing the setlist so that they switch to oldest material with 6-strings to allow technicians to re-tune it.
Now that I watch the live videos from recent shows I noticed he also had another 8 string he played at least one song on:

But he also used the white one to play few others.
Maybe it would be worth it to have a look at the two other songs from the new EP so see if the low B reoccurs…
On the topic of scale and strings, I de-tuned mine to low B on the 8th and it is… playable, as long as I hit it very lightly, still there’s some fretbuzz, but otherwise I think I could use it that way.
Also, nice playing there.
EDIT: looking at the level of detail and overthinking I do here, I am beginning to suspect I truly am neurospicy lol