PV1 said:
Yes. I've dreamed of being able to do this.
How much does real driving range improve,
The title of the video ends with "after battery upgrade", so that depends on what capacity and health the replacement battery has. [ Edit: one would imagine that it would be of the order of 95/48x ≅ 2x the capacity of the factory new-car range, depending on several factors. ]
and is there a flash back to stock capacity?
I saw two file names ending in .bin; they had the same name except that one had "_95Ah" (or similar) and the other did not. So it looks like one is the original image as extracted somehow from the ECU, and the other is the patched or recompiled version that has 95 where the original had 48 (representing the battery capacity in amp·hours). So yes, I'd say he could have selected the other file, and replaced the firmware contents with the original.
95 Ah sounds familiar; I think that's the nominal capacity that the Oz DIY NMC cells use, which fit in much the same case as the originals. My guess is that Kolyandex or someone he knows is able to purchase these same NMC cells and perform the mechanical cell swap.
When I was looking into this, I got the impression that there was a limit to what value the firmware could store for the battery capacity. I can't recall now, but I think it happened to be pretty close to 95 Ah, by a lucky happenstance. But if battery technology improves much beyond that, it may not be possible to use this technique.
It would be interesting to know if he only changed the nominal capacity, or also modified the Soc versus cell voltage table.
This post has a really rough auto-translation of the speech from the video; perhaps the answer is in there. It didn't leap out at me at a quick reading.