Ok, so here's how to get rid of the dark band. Use "videocrop" to crop it away!

The new pipeline to produce a properly sized image with no dark band:

gst-launch-0.10 v4l2src device=/dev/video1 ! "video/x-raw-yuv,pixel-aspect-ratio=(fraction)1/1" ! ffmpegcolorspace ! videoflip method=4 ! videocrop right=122 ! xvimagesink force-aspect-ratio=true