Those aren't some numbers, those are tab identifiers, assigned by the web browser. We can add title to each tab in the list, but title is constantly changing, and soon will become irrelevant to those videos that were detected. Note that there is a small button 'Switch to tab' that switches to the tab, on which videos were detected.

We're rolling out version 4.12 on the next week, where All videos page is going to function like the old Downloads page. Hope you'll like it and will yet rate us with 5 stars :-)