Design a video streaming service similar to YouTube that allows users to upload, view, share, and interact with videos. The service should support a large library of videos, accommodate a high volume of concurrent viewers, and provide a seamless viewing experience across various devices and network conditions. Consider factors such as content delivery, video transcoding, storage, user authentication, recommendation systems, and monetization options in your design. Discuss how you would handle video ingestion, content distribution, and user-generated content moderation. Additionally, address scalability, fault tolerance, and data privacy and security measures. Provide insights into the technologies, protocols, and architectural patterns you would employ to build and deploy this video streaming service effectively.