For me, about the same as Shutterstock. Far from the best however.

... it was super slow, I don`t now why... and it`s strange that both sites are experiencing strange (higher than normal) number of views, but not followed by sales... slowed down suddenly and I got no clew what`s happening...

Apparently everyone has different results.
For me SS is the number one by country miles, always, constantly, by huge margins.
At number two is generally either Pond 5 or Fotolia, but in the last couple of month Fotolia has been relatively quiet, so Pond 5 has done better (and I have very high prices on Pond 5).
The funny thing is that it all works in a way that at the end of the month for me the grand total of video sales is always the same, and I am not complaining at all.
It is much more like a wage for me, rather than a free lance work. Don't ask me why, as I cannot tell you
:-)

The funny thing is that it all works in a way that at the end of the month for me the grand total of video sales is always the same, and I am not complaining at all.
It is much more like a wage for me, rather than a free lance work. Don't ask me why, as I cannot tell you
:-)

I can tell you why.

It's because you have a good portfolio that is reasonably big with clips that are usable commercially in a great number of projects. In order words: you have produced enough content that many buyers want to use. You have many of the most common search terms covered.

You also have really good search placements for a few clips on very common search terms, which is ideal. Those clips are not the same on the different agencies, which explains the variation in sales, and also why you end up with approximately the same sales over time.

You have a number one clip on Fotolia for one of the most common search terms, but Fotolia overall don't sell as much footage as Shutterstock or Pond5 (yet), so it doesn't take that many sales to get there. But when a customer over there does need a clip like that, they will absolutely find it.