Ok, so i recently realized that the particles don't show up just like in the video...

to fix this... first download this .pcf file which are saved the particles of merasmus:
Here[nemesis.thewavelength.net]

then go to your tf2 folder and open tf2_misc_dir.vpk.

then go to the particles folder and search for halloween.pcf. Just like what i did in here[imgur.com]

then go to your garrysmod folder and then drag the pcf file to: garrysmod/particles.

then you open the particles_manifest.txt and then you write: "file" "particles/halloween" just like i did in here: Imgur[imgur.com] and then save it.

Now the particles should show up.