Bear in mind that video clips are usually linked to their audio, so if either track is moved the other will be as well - to remain in sync.
To insert a new clip, make a split. Do this for all tracks by clicking the scissors
or the SPLIT button.
To restrict the split to specific tracks click the chevron to the right of the SPLIT button..
Select (highlight) all clips to the right of the split, then drag them to the right, leaving a gap. If they snap back hold down <alt> while dragging.
Right-click the desired insert clip in the bin and PLACE CLIP ON SEQUENCE AT CURSOR. Or simply drag it to the left-margin of the gap. Arrows will appear.
If you make a mistake immediately press <ctrl-Z> (EDIT | UNDO) to backtrack, step-by-step.
Save Project File AS frequently, giving it a unique # or name, so as not to overwrite prior saves. Save Project Files (no AS) will overwrite. Then you're protected and can double-click a VPJ saved file (which is not playable) to reload the project as it was when saved. Don't delete or move source files.
Record_2020_08_19_11_09_42_899.mp4