Nagra found a way to "sell air"....all major companies do it.
It's our job to not buy it.
This is rather silly thing to say.
Nagra use the same case for both the low capacity and high capacity battery pack - the "empty space" would be filled by the second battery pack for the hgh capacity pack.
In fact, a sensible way of doing things, as making two different sized cases would be more expensive.
What the original video was doing was actually extremely dangerous - Lithium batteries need to be properly balanced - replacing a cell is very dangerous.
These sort of batteries have been known to catch fire or explode - so Nagra ensure that the batteries fulfill all conditions for them to be taken on-board an aircraft.
Yes, a Nagra battery pack is expensive, but not unreasonable when you consider that the pack is a high quality unit made in small quantities.
And Nagra *do* re-battery a battery box at a very reasonable price and should a battery pack fail - you do *NOT* have to buy a complete new box - just get the batery pack replaced.
Don't forget, You Tube videos can earn the producer lots of advert revenue - so hyping something up and saying something contreversial will earn the video maker *lots* more advert money if it goes viral - so it pays the producer to hype things up, rather than giving a proper reasoned explanation.