I am experienced computer engineer. I joined to connect.appen.com and did some tasks. They didn't pay my money. They removed the tasks from their control panel and replied me like "they are too busy" or " too many applications done" or "the reviews are requires too much time" etc. at the end i couldn't receive my money. By the way months passed, they told me that please wait. These tasks were little tasks. But i trusted to them and completed the tasks successfully. They are still sending many emails for new projects but i will delete my profile and never do anything on appen.com.
Please don't trust to them, you can't get your money after tasks done. This is my friendly notifications for freelancers that will join to connect.appen.com
If you want to make some extra money, this is definitively an option. You get paid just submitting photos of videos. And don't worry, your image is totally safe.