Need to order quick!?

what kind of substrrate do they have for their floor?

YouTube - 24g aquapod nano tank

and i was wondering how do u hookup a refugium to a 24g aquapod?

 

Can't really tell which substrate, but it looks like white crushed coral which is what I have. You can get it at your local LFS.

Can't answer the latter half of your question, Sorry!

 

Looks like sand to me. Something like the Fiji Pink here, very common substrate and requires less maintenance than crushed coral.

Substrate for Saltwater Aquariums, CaribSea

 

With a healthy mini reef like that, it is definitely not crushed coral, but an aragonite sand, like oolitic or sugar sized. It may also be pink Fiji, but it's hard to tell since this youtube had low quality video. Besides, it's hard to see the pink under the actinics.
If you want to hook up a fuge to a tank like that, you will have to drill a couple bulkheads into the tank walls, one for drain and one for return. You can also do an hang on overflow, but finding one that will fit is the hard part, most will be custom made.