You could just replace the original weapon HUD if you wanted, in the video he will explain how to place a new health HUD, its the same process for the weapons except you will need to do more work to incorporate all the weapon images used in your game rather than just one for the health.
The commands are all in the global.lua such as g_PlayerGunName and then you can just show a set image based on that result.
Unfortunately there isn't a quick fix as far as I know to only hide the health and not the gun HUD
