Edit
Undo
   • Undoes the last change made to the active movie.

Cut
   • Clears the selected segment of the active movie, or, if none, the current frame.
   • Saves it to the clipboard for use with Paste, Add, Replace and Add Scaled.

Copy
   • Saves the selected segment of the active movie, or, if none, the current frame to the clipboard for use with Paste, Add, Replace and Add Scaled.

Tip:  Hold down option to turn this command into Append.
   — Append pastes the selected segment of the active movie onto the contents of the clipboard.

Paste
   • Inserts the contents of the clipboard (obtained from Cut or Copy) after the current frame of the active movie.

Tip:  Hold down option to turn this command into Replace.
   — Replace inserts the contents of the clipboard
         · unlike Paste, this overwrites the current selection.

Clear
   • Clears the current movie selection, without saving it to the clipboard.
   • Pressing the delete key has the same effect.

Select All
   • Selects all of the active movie.

Tip:  Hold down option to turn this command into Select None.
   — Select None deselects any selection in the active movie.

Add
   • Inserts the contents of the clipboard as a separate movie track
      · the added movie track starts at the current frame,
      · this is useful for adding a soundtrack to an existing movie.  

Add Scaled
   • Inserts the contents of the clipboard as a separate movie track
      · the added movie track starts at the current frame,
      · this is useful for adding a soundtrack to an existing movie,
      · the duration of the added movie track is scaled to fit the selection
         — (stretching or squeezing the clipboard contents to fit).

Crop
   • Clears the parts of the movie that are not selected
      · it reduces the movie to the current selection.

Copy Frame
   • Saves the current frame as a PICT image to the clipboard.

Export Sound
   • Saves the movie soundtrack as an AIFF sound file.

The following diagram summarises these editing operations.