It can mean a couple of things. You can have a look at Library items in Red or look at others here

To put simply, the files have lost their relationship with their downld list brothers. This might be due to them being deleted off the downld list or just for some reason lost their relationship with the original source.

It is possible to continue some of these. Select them & use the Resume function. Then go back to the search window & do a search for the topic.