I appreciate your comments, but I am going to insist that we move on. Perhaps if we have time at the end of the meeting, we can come back to this. Then move immediately to the next agenda item. Keep in mind that this approach may result in some ruffled feathers. It may be appropriate to speak privately to the long-winded person after the meeting to explain why you felt this was necessary so that meeting goals would be met.
Some people are naturally reticent to speak in meetings.
The chairperson must respect individual differences of this type, while at the same time setting up a climate that increases comfort levels, and inviting quiet attendees to be more involved. You can ask silent group members to be involved. The way you do it is important. The best approach to involve a shyer person is to pose a specific question to that person. The question should be one that the person can answer easily.