Is there any way I, as a viewer, can change the aspect ratio of a video where the uploader got it wrong? It's driving me mad! Can't believe YouTube doesn't have anything for me to fix this... Does it?

Edit: is there perhaps a program for viewing YouTube videos outside of the browser that has the feature? For instance, Miro can show youtube videos, although unfortunately it doesn't seem to have a feature to adjust the aspect ratio either.

Bounty: looking for new options, since iDesktop can no longer do this.