VideoPad (ca. 2011) doesn't support copying and pasting. It does, however, support duplication. It has the same effect as copying a clip, move the cursor to the next clip, and pasting the clip. You can also duplicate a block of clips. To duplicate a clip, right-click on the clip and select Duplicate. Alternately you can use the keyboard shortcut Ctrl+D. The duplicate option, for some reason, only appears when you right-click on video clips, and not on audio clips. For audios, use the keyboard shortcut Ctrl+D.