I haven't seen Oprah, so I am answering a question that I *think* you are asking: how do you put a background behind only a string of text (and only the string of text) and leave the rest of the video area blank/transparent?

I stumbled onto a different solution as above, hence this post:
Create a text media in the "text" track (Track 1 by default). Type in the text. Choose the placement of the text (e.g., "Bottom Center"). Then, choose "Properties" and select the text color and the background color. I used a semi-transparent grey background and a white text in order to put date captions on one of my videos (sort of like a documentary on Discovery Channel). Here's the final trick: after closing the media and you see your created media on the text track, choose the pan/crop tool. Set the "Stretch to fill frame" item in the "Source" to "No" (default is "Yes"). Then, crop and move the frame to behind the text. This leaves the entire screen blank (transparent) and only the text and ribbon showing (again, depending on the transparency of the ribbon).

The benefit of this solution relative to the prior post (if I understand the prior post correctly) is that you have a single video item on one track that can be copied and pasted alone elsewhere (then edited to suit) vs. cutting a pasting from two tracks. I also applied a fade in/out to this clip that is preserved in cut and paste.