While everybody focuses on the transmission, what exactly are your 'society members' connecting to?
First off, putting a CCTV feed outside a security room is in itself a pretty slipshod way of handling security. Feed is privileged information and frankly the less known about it the better. This way basically a large number of people know where the cameras are and what they point at, and can basically nullify any advantages of the entire setup. It only takes one disgruntled member to change the complexion of the game.
Second, I assume what you will connect to is the DVR itself, running as a service over an IP on your local network. You will be limited to the max number of simultaneous users in the DVR (usually 10 or 20). In this case all you need to do is connect your wireless AP to the same network and when your 'members' connect to that network they will be able to access it using their mobile browsers or any app that can connect to it directly over its IP address.
Now to the broadcast itself, you will need high power APs and directional antennae. This is a very wasteful way to broadcast - wastes energy, will cause problems because the frequency and power levels are unsuitable and may even be illegal, interfere with other gadgets and so on. You can use several low-power APs but you'll need lots (think 1 for every 3 floors). G network is better suited than N because it has better transmit power and greater cut-through concrete walls, and will have sufficient bandwidth for the application.
The best way to do this is create a DDNS for your DVR and have members use their mobile internet connection to access the DDNS. You'll need a 2Mbps connection or a 1Mbps connection with 1:1 upload ratio, known as enterprise connection. 1Mbps should be more than sufficient for 3-4 simultaneous users.
I thought it was L shaped. This looks really complicated if you go the wireless way. I can't think of anything. 
