Learn more about total control over the (limited) possibilities of your D90 in this dvxuser thread.
The D90 videos show severe stairstepping. See this thread at dvxuser.com. They can be removed with the frei0r plugin d90stairsteppingfix (not yet available in frei0r 1.1; Compile frei0r from git instead if you absolutely need it already).
Sample images. Without filter (directly from the cam):
With the d90stairsteppingfix filter applied: