I've seen that video about Saturn RE2 before, though it's not free of mistakes...
For one, development was absolutely being handled by Nextech, with Capcom staff - mainly Hideki Kamiya and Shinji Mikami - acting in a supervisory role. As with the first game, it's quite likely that Sega also provided some technical assistance, since Nextech had strong ties to this company, too. Earlier in the Saturn's life, Nextech had been credited for work on two Sega Ages volumes, not to mention it fully produced Cyber Speedway for Sega along with being heavily involved with the first Sakura Taisen.
Years ago, I was in contact with someone who worked at Sega's European offices, and they were able to provide quite vivid recollections of certain games that never saw the light of day on Saturn. Between their memories and comments I've seen from another typically reliable source over at a fan forum, my belief is that Saturn RE2 was roughly 15% complete when Capcom ordered the plug be pulled, instead tasking Nextech to begin work on what became Code: Veronica for the Dreamcast. Also, this absolutely did not use the 4MB RAM cartridge, with much of the problem being CPU limitations.
Perhaps the biggest detail it seems most people are missing is whether Saturn RE2 would have been a conversion of the "1.5" scenario or its eventual retail counterpart. From what I can remember, the original Japanese announcement that Saturn wasn't going to receive its own version of RE2 came in February 1998, and it's no secret that the PlayStation was Capcom's lead platform, so it's not as if work on porting anything to the Saturn could take place until a finished source for RE2 existed.
Now, if my understanding of the RE2 timeline is correct, the last known monthly build of "1.5" submitted for Shinji Mikami's approval was produced in December 1996, and following a break for the holidays, this prototype was reviewed before it was decided the entire project should be taken back to the drawing board. I'm quite certain this specific version is what ended up being featured in video form on the Biohazard Complete Disc, even though it's a lot more polished than the circulating November '96 build.
Anyway, the real mystery of when exactly Nextech was working on its Saturn conversion of RE2, because Capcom wasn't yet at a place where it could give finished code and assets for this project, but the earliest retail build wasn't released until January '98 - just a month before the conference I mentioned previously. Saying that, if Saturn RE2 was only 15% done when Capcom ultimately cancelled this, maybe Nextech took delivery of complete files in late '97 and had just a few weeks, meaning they were using the retail scenario as a base?
I was really hoping to see some kind of Capcom reunion documentary with Mikami, Kamiya and other key Biohazard/Resident Evil team members discussing "1.5" for its RE2's 20th anniversary celebrations. However, outside the Elza Walker skin that was included in the remake as DLC, there wasn't really any other acknowledgement of this prototype - not even more footage or a playable build fixed up as an unlockable extra. Since then, Kamiya has taken to blocking non-Japanese people trying to reach out to him via Twitter, so unless that December '96 build leaks, I fear that the door has been closed on further information surfacing.
Of course, I have faith that Team IGAS and Loboto 3 will be able to faithfully approximate the essence of what Capcom originally intended for RE2, plus it's been suggested they may have access to elements that were present in the last-known "1.5" monthly build along with their own recreations, which come from years of experience, plus the community's wide research. As for Saturn RE2, I'm not holding my breath due to how little has ever surfaced through Nextech. Being a studio with a long reputation for handling outsourced projects, I reckon security would be high on its priority list if it wants to keep getting new contracts.