Re: Retouching video clip - length of clip changes!?

I don't think you've lost any frames. Seems the 24fps is being interpreted as 30 fps at some step in your process, maybe on re-import to FCP. (multiply your 104 frames x .8 and you get 83 which is the exact diff between 30 and 24 fps.)

I'd check the re-imported clip in FCP and confirm that it actually is being interpreted as 24 ((23.98), if it's not then manually change it.

Also confirm that your pshop timeline was 24 and not 30. In Pshop when you create a new document, the default timeline duration is 10 seconds and the frame rate is 30 fps. To change it, from the Animation palette menu, you can choose Document Settings. Enter or choose values for Duration and Frame Rate.

Even if the pshop timeline was set to 30 I think you should still be able to interpret the 30fps roto'd clip as 23.98 and your work will be OK.