I export a motion stablized clip with alpha into premiere and to fill in the missing border area, I use the first frame of this clip as a static background. I'm not familiar with AE so I did the minimal work in AE.
This works ok except there is an obvious edge at the alpha border. I could reduce this by adding a color key effect (black color) to the imported stablized clip and set edge thin and feather to their max value (5 and 10). It would be better if the max values are higher.
Alternately, I could add the background in AE and then export it without alpha. Would it be easier to feather the edge of the stablized video clip inside AE?