I’ve been selling stock media for a year and a half now. I am almost to the point where I can make a full time salary off of it. I do sell mostly animated backgrounds, which I actually think is harder b/c they take longer to create than some footage.
But to answer your question- Yes- it is definitely worth it. Especially if you already have a library of footage stocked up! Right now that footage is sitting, rotting on your shelf– it could be making you money! I’ve tried most of the major stock sites and sold on most of them for awhile. However, I got tired of the hassle of uploading to multiple sites so I choose my favorites and stuck to those few.
I upload mostly to Revostock.com. They had the easiest and most hassle free upload/approval system of any of the major sites. They also have a wonderful producer community and their technical support is excellent. Their royalty rates are 45% for a non-exclusive clip and 60% for an exclusive clip– you can choose your exclusivity on a clip by clip basis too! Check out their forums– they recently had several producers say why they love their site and one of them mentions how much he takes in each month from the site. You can sell audio files and After Effects projects there too if you have them!
Hope this helps give you some more information about the stock business.