I am wondering how this works...I see people say they make a good living doing this but you must need a good amount of coin to make this work.
Anyone that does this give me some insight into how this works?

Buy from one platform at market price (btc-e, bitstamp) and sell with margin on platforms like localbitcoins. Repeat this. Repeat this again. And keep repeating it. You will earn good profits.

At whatever price you are buy, just make sure you sell it at the higher price than that and maintain your accounts well.