dl.dropboxusercontent.com/s/8pmgiabr9gw0vyo/pdLHXfIXxS.mp4

Here:
C:\Program Files (x86)\Steam\steamapps\common\GarrysMod\garrysmod\lua\menu

background.lua:
pastebin.com/raw/kAvmLz0w

mainmenu.lua:
pastebin.com/raw/iaMpYWH2

Cool command this will change all files within that folder with the file extension .gif to .jpg

ren *.gif *.jpg