White thing - Cloud?

The image was taken with aft camera when ISS was over South of Atlantic Ocean. What could that white thing be? It was part of the clouds, not an optical artifact.
Date whe the image was captured (UTC): 
Saturday, February 7, 2015 - 03:00


Maybe you know this video:
Is it a similar or different phenomen you recorded?

That video you mentioned is actually showing a small feature that travels together with ISS. In the picture above the "white cloud" was part of the cloud system.