Have you tried using the "snapshot" feature in VLC? Much easier than screen grabbing and you can go through the files at leisure.
(On the Video menu, or
opt-cmd-S)
I've used it a lot recently on an iMac, it works well and you can single-frame forwards with the "E" key. Haven't found a way to single-frame backwards; nearest is "Very short backwards jump" (Cmd-ctrl-left), which seems to be ~75 frames
eta- you can set up the destination for the stills in
Preferences, I can't remember the default location.
Edited by billford (Fri 05-Sep-14 06:21:59)