Buy this book and read it cover to cover . I did. And Ive been editing for 30 years...
For the Video, you can do a PiP (Picture in Picture) and limit that to the area of the Title.
Also, if, for instance, you created, say a Lower-Third with a Shape (in Titler), you could place your PiP into that Shape, and then do another Title with Text, etc., above it.
It would work the same way with a Still Image, which would be done as a PiP, and supered over a Shape, if that was desired.