Two Cool (Free) Plugins for Adobe Premiere Pro
This plugin allows to create a simple alpha mask on the source clip and composite it with the existing alpha channel by adding, subtracting or intersecting. Both rectangular and elliptical shapes are supported. They can be repositioned and rotated.
This plugin allows to create a vignette on the source clip. Both rectangular and elliptical vignettes are supported. Vignettes can be repositioned and rotated, applied in any color and blending mode available, to the inside or to the outside. Alternatively only the mask can be rendered, replacing the source layer altogether or the vignette can be filled with transparency.