I have searched through the beginner's guide and haven't been able to find answers to these questions. They must be really obvious or something

What i want to know is where to put demo vids in my Quake III directory. If i search for "demo" on the forums, i get a truckload of posts about the demo version of the game, and likewise with google.
I've tried putting the demos i've downloaded into the main Quake II Arena directory, in the baseq3 directory, and i've even created a sub-directory in baseq3 called "demos" and put them in there. No success. I seem to be able to get most of them to show up in the demo page when i load up the defrag mod, but half of them won't load, and the ones that will don't actually do anything. They just start in 3rd person behind a player, who will just stand still and do absolutely nothing all day.
The other thing i wanted to know concerns the maps availabe in this link: http://www.trickingq3.com/Tutorials/Str ... orial.html
They're .bsp and, as i understand from the begginer's guide, there's nothing wrong with that. However, the maps do not show up within the game, and i wanted to make sure i've got them in the right place. They were downloaded as zip files and i unpackaged everything within the zip file into my baseq3 folder. This means there are now sub-folders in the baseq3 folder entitled Opc1.pk3 and Grid.pk3
The Grid folder has a grid.bsp file in it, the opc1 folder just has a bunch of textures, and no apparent map file. When i try to load them from the console in the game, it tells me it can't find them.