There is new item command, but it will overwrite by default. I plan to add options to customise behaviour of this command: overwrite or insert, on which track, etc.
As a workaround I can suggest this:
- use select all clips after playhead command (playhead should be on the cut point between 1 and 2 clip)
- move clips to right (use keyboard shortcut command)
- add black video (new item command)
To customise duration of black video you can go to Preferences > Timeline and change Still Image duration to 7 frames.
