i can't help you with mac, but in your editing program, you can see the vignette of the footage.
My workflow with the hmc150 is to set the buttons on the left of the cam (USER 1, 2, 3) to "MARK CLIP".
I mark the clips while recording or on play mode. It adds a little orange "M" on the clips.
Unfortunately I can't see the "M" on the computer. So in the evening, I protect the marked clips on the camera (OPERATION / CLIP PROTECT, it adds a key on the marked clips).
Once I made sure all the needed clips are protected, I do OPERATION / DELETE/ ALL CLIPS.
It gets rid of all the unwanted clips while keeping the protected clips.
It's a bit risky so you have to be focused.
If anybody has a better solution, I'd love to know it.