At the moment Veeroll finds all videos.
There's no downside to having non monetized videos in your campaigns. They can become monetized at a later stage as channels are free to turn monetization on or off at any time for any video. It's best to include all placements therefore, because if your campaign is running for a considerable amount of time your placements may become monetized in the meantime.
You don't need to select only monetized placements to run even very large and successful campaigns. We are getting regular advice from leading agencies in this matter who act as advisers to Veeroll.