I am still using Vegas 9 Trial. I have a movie on the lower track. Above it is a still on which I have used event pan/crop so it starts zoomed in close and spins whilst zooming out to fill the frame at normal size and the right way up so it covers the enitre movie screen.
The still is the same size as the video (720x576) but as it approaches the end of its spin, you can see the underlying video around the edges. (If I haven't explained that well: imagine having two postcards one on top of the other and slightly rotating the top one and you will see the corners of the bottom one.)
To overcome this I have put a video track above the movie clip and below the still picture and at the appropriate point used solid colour black from Media Generators (because the still's background is black) to fill the frame and hide out the corners of the video.
Now it all works fine on Vegas preview, but once it is rendered, the corners of the lower track are still visible as if the middle track was not there.
Have I missed something?