Unfortunately, narration and quality of the video is barely average.
In the intro he explains problem of lack of heating in Thai Vigo. Then he briefly explains modifications required:
Changing the evaporator unit (because factory fitted part of Thai Vigo doesn't have any provision for heating pipes to be connected)
Sourcing and connecting heating pipes to the heater and to alloy hose connector on the engine head (that comes before the radiator top hose). But that can be done with the help of a lathe machine operator to make provision of it.
According to him, it's quite a hectic job and can take 7 - 8 hours, that too if the mechanic is proficient enough. Then an electrician shall wire up the connections with ON/OFF button on vehicle's dash and disconnect a/c direct operation with fan knob.
Then he covers how it was done at a workshop. But he doesn't narrate with much details. Also, it is shown in fast forward mode. So it is hard to concentrate.
You can check amayama for evaporator unit and pipes.
That much I could understand from this clip. Best of luck with yours to be imported vehicle.