In releases that snap back when clips are dragged to the right, holding down <alt> should override that behavior.
If Videopad is reinstalled (no need to re-download) the snapping may cease. Sometimes it takes several tries.
To add clips at precise split points use these buttons 
to position the cursor at the split point.
Then right-click on the to-be-added clip in the bin and Place On Sequence at Cursor.
For better visibility expand the timeline, using the slider at the bottom-right of the window. 