MicrostockGroup

Is it worth to be an exclusive video contributor at iStockphoto?
Any exclusive contributor can share your experience ?

Absolutely not.
I dropped my video exclusivity long time ego and never regret it. Now I sell video on 3 sites.
Pond5 alone earns me more money than when I was exclusive. Logic, they sell more and pay 50%. Another interesting thing at Pond: I can fix prices so if I consider a file "Vetta" quality I can increase the price.
Shutterstock is not working very well for me and earnings are comparable with IS.
I don't upload to Fotolia as I consider them as the worst video (form contributor's side) site.

I also like revostock, slow sales but hopefully they will pick up, if footage becomes more widely used.  I have sold a few clips with CanStockPhoto for a nice commission.  SS haven't been very good with footage, I've no idea why they are letting their rivals establish themselves in a potentially lucrative market.  I sold a clip on clipcanvas with not many uploads.  I will give them a chance, as the site looks good.

It is ABSOLUTELY NOT a good business practice to be an exclusive contributor on any site (in general). You can read more about my experience going non-exclusive from iStockphoto on my blog at www.stockvideoseller.com. It's a bad idea on several levels. Financially, being the foremost. You'd do better spreading your work out over the top income producing sites. On another level, if you are doing this as more than an occasional submission, you'll expand your skill and knowledge about the stockvideo marketplace by selling on multiple site. For example, some sites accept editorial and some don't. Some won't allow anything not from a tripod. Some will. iStockphoto as strict guidelines on copyright (pics of your random dog get nixed - might be someone's dog. That dog needs a release!)