It doesn't mean anything, seriously
It just means that DVD SP is ignoring two non-DVD files inside the VIDEO_TS folder. Those two files are created by DVD SP to keep track of changes on your project, comparing to your built DVD folder. As a test you could drag some computer file (say, a Word document) inside the VIDEO_TS folder, and you'll see DVD SP now report that three files won't be included!
In other words, competely normal and expected behavior.
Adolfo Rozenfeld
Buenos Aires - Argentina
www.adolforozenfeld.com