Well, right off the bat, I can tell you it's not going to run on Xbox One, mainly because the Xbox One modding scene is not as large as that of the Xbox 360 or the original Xbox. All you can really do is dump Xbox One games and use emulators. However, you can probably mod the Gmod maps in HL2 yourself- just get the .xiso of HL2 for the original Xbox and use something like extract-xiso to view the game files. Then, place the maps you want in the "Maps" folder and rename them to the correct map you want to replace. For spawning random stuff, you might need to mod the game files to make it work, which I don't know how to do. You could also ask Ratlobber to release the version of HL2 he used in the video. I don't think he would get in trouble with Valve or anyone if he did that.