After reading their FAQs page, I have found that they get their tasks from Crowdflower and you can read more about the site here
http://coinworker.com/help I guess basically they are like other sites who use Crowdflower tasks as a way of earning except they pay in bitcoin versus other currency. I'm not sure if it makes them more legit because they use Crowdflower or not. I think I will just stick with Crowdflower Elite for doing these tasks since they pay higher amount for the tasks. I wish anyone luck if they decide to try out Coinworker though.