This is false. That video linked is a video of Warcraft III Patch 1.31. The program I have been working on began around that same time, and was not playable even slightly until 2020 at which point the
earliest prototype did not have inventory. (The post linked is from 2019.)
Edit: Admittedly 2 years later after the 2019 post in question was made, I did develop the same system in about 30 minutes on my external program and feature it in a video, but that is not something that can be used with War3.
However, the 1.31 map with that inventory shown in that video stopped working on Reforged. All the icons flipped upside down and broke and stuff. I didn't really understand why, but these systems are a giant hack.
How about you just use this tasyen system or something like that?
Introduction TasInventoryEx is a custom UI system/addition for Warcraft 3 V1.31 or higher, In vjass or Lua. With it heroes can equip more items (use item-boni). There is a version (jass or vjass) for Warcraft 3 V1.26 without customUI, using an Unit as substitude. Details The storage UI is a...
www.hiveworkshop.com
I think his solution with multiple inventories if I understood correctly when I heard him talking about it, is probably better than the solution I was using in the video there