I want to know how to black out the map

Do you mean you want to NOT show linedefs in the automap? If so, you should just be able to flag the line as hidden. In UDB, open your map and enter linedef mode. Select and then Right-click on the line(s) and select 'Not shown on map'.

You can drag/multi-select many lines if you want to hide everything.

In that video, he's talking about code that is written in the MAPINFO lump (which is a different thing to ACS). If you open up myhouse.pk3 in SLADE3, you'll see this:

If you click that file and scroll down, you'll find this:

The values are set to "00 00 00", which correspond to changing everything on the map screen to pure black.

if I open slade in a different project other than my house, MAPINFO isn't one of the options? IS there a way of getting that in with the files

You can just create the file yourself within SLADE.

Right click and select 'new entry':

Type in MAPINFO, and make sure you have 'text' type selected:

Once you've done that, select the newly created file. Then you can put the text in.

Alright, I made a new entry titled "MAPINFO", now is it as easy as literally copying down all that string of text (Automap {base + "Doom" ect.})

No, you have to perform a black magic ritual and sacrifice a virgin born on 7th moon...

The 7th moon? damnit, I missed my chance, now I gotta wait for saturn to be in retro grape or whatever the fuck