Grass Valley NewsEdit LT v.4.1 - Manual (Page 120)

Chapter 7 Fine Tuning and Advanced Editing
120 Digital News Production
3. Right-click and select Insert Filler .
The Filler Properties window appears:
4. Enter a duration for the filler and click OK .
The Timeline updates with the filler inserted into the sequence.
NOTE: You can also insert filler between Mark In and Mark Out
points on all tracks that are active. You cannot add a transition effect
between a clip and filler.