'
BTV Pro' has a feature to "average" several frames together. "..To create a noise-free image, the frame averaging feature takes a number of frames from the video input and averages them together to produce a single image. This can significantly reduce, or even eliminate, the noise in the video signal. This works because the image is constant but the noise is quickly varying so over several frames it averages to zero.."
But perhaps the adjustment you want is more drastic. (..And I don't know if 'BTV Pro' is a 'Universal' app, so it may need to run in 'Rosetta' on a MacBook - thus making it a bit slower than usual..)
As for other "copy and paste" movie-editing programs; '
MediaEdit Pro' (..there's a free trial download..) lets you 'paint' on video frames, but I don't know if that lets you do
subtle touch-ups ..read more about it on their website.