From Nikon Support

Why are there spots in the video I shoot with the D7000?

We have received reports from some users of the Nikon D7000 digital SLR camera regarding the occurrence of noticeable bright spots with movie recording under certain conditions.

Nikon believes that these bright spots are not normally noticeable, and therefore do not indicate a problem with practical use. However, with further investigation of the reports received, we have confirmed that bright spots may be noticeable when recording movies of especially dark scenes or subjects.

In order to provide our customers with better products, Nikon is currently preparing to release a firmware upgrade with measures to reduce the occurrence of these bright spots for the D7000. Further details will be announced at a later date.