for such a video source website, I believe we should definitely start with the basic functions first. I can list a few functions, we can then discuss and let me know what you think on these items:
We will definitely need some low-latency play-back mechanism, and since this is YouTube, I assume the global users would be huge, so high-availability is a must, as well as scalability.
Estimate the scale of the system. Consider daily active users, read/write ratio, storage requirements, bandwidth, and any relevant QPS calculations...
We will need the following RESTful services:
Additionally we need a Streaming API for users to watch videos
Describe the overall system architecture. Identify the main components needed to solve the problem end-to-end. Use the diagramming tool to create a block diagram.
Define the data model. Identify the main entities, their attributes, and relationships. Consider the choice of database type (SQL vs NoSQL) and justify your decision based on access patterns...
Deep dive into 2-3 key components. Explain how they work, how they scale, discuss tradeoffs, capacity, and any relevant algorithms or data structures.