Ah, sorry, I neglected to click on the image previously.
You could save some time by just rendering the footage from VisionLab with an embedded alpha channel. Linky.
Out of curiosity, why are you compositing it in AE instead of just completing the composite in VisionLab?
You could use a value key to remove the black, or just switch the composite blend mode to screen or add, or something else that will remove the black areas.