Down and dirty and did I say simple?
Alternately in Vegas Pro under the transitions tab is a group of transitions called gradient map. In this group is a paint stroke or splatter like transition. First set the fade time on the clip(s) then add this effect by drag and drop. You'll find it's more like a drippy paint than a stroke, perhaps you can fiddle with the settings of this transition to season to taste.
You could use this effect with a solid background color field and blend with your next scene, just another track to add, but be aware that you will may need to play with the compositing method to see what looks best: add, subtract, dodge, burn, difference, etc.