Had a couple of footage sales this month. Including an HD for $14. I had a long back and forth with support trying to work out how I could get such a low royalty, when the cheapest credit is $0.78 (cheapest for footage sales), so the minimum I should get is about $25, as I have opted out of the API Partner sales.

Long story short, the final answer I got was:

These credits come from our PROMOTIONAL ACTIVITIES such as the case of giving away CREDITS to prospective clients whom we think, require a bit of a test drive on the 123RF system before they make their first purchase.
A demo if you like, we give these out at our discretion.
The client DID NOT PAY for these credits, it's given to them courtesy of 123RF.com.

Therefore, seeing as 123RF is giving away these credits, it comes out from our Advertising and Promotions Budget
and there is a cost attached to it - 45 cents per credit given away.  
I do hope you'll see this a bonus from your business partner 123RF as the prospective client did not pay for them in the first place.

Which still doesn't compute... unless they are taking their 50% cut out of the money that comes out of their budget to pay me.

I sold one 240p and one 480p clip for the grand total of $11 

I was averaging about 1 sale per month there. I reached payout last week, and closed my account.

I figured that when my commissions were cut by 30% (?) this January, it would take far too long to reach another payout. Plus I just couldn't see earning so little per sale on a site that hardly sells. So I closed my account.

If they hadn't cut commissions, I'd have happily stayed with them. But as it is, it felt a bit like bait 'n' switch. ("You'll earn 50% commissions" ... but they forgot to add: "for the first 9 months only!")