Thanks, Bill. So you're saying when you want to empty your SD card you simply format it in the camera. Seems a lot easier than deleting the clips one at a time!
In regards to important harddrive files, I screwed up an external trying to reformat it the wrong way (give me a break my OS is in Greek, not English!). Do you know if there's any way to get those important files back on there. I have another external, same brand, maybe I could copy the files over should be able to access the empty harddrive some how.