If you actually watch the video, he explains (9:25) that 's just the shell of the old battery (mostly empty). It is not a 2nd battery mounted for use.
You should not try putting [a] full battery on LEAF; it will probably break under the weight.
Thanks for the information.
Yes. Love this car (if that wasn't already obvious).
I have the same feeling about my 2012 red Leaf with upgrade wheels - love it. The only problem is it will not make it to my rural property on one charge (~100 miles one way). Still trying to decide how to resolve this so I don't have to take my (work) Suburban. every time. Truly wish there was an option of upgrade here in Houston. How much to you think this entire swap will cost you assuming you will part out the 2020??
This place looks promising: