Build and optimize a video playlist component
Company: Netflix
Role: Software Engineer
Category: System Design
Difficulty: medium
Interview Round: Technical Screen
##### Question
Design and implement a video playlist component in React (functional components) that meets the following requirements:
1. Display a list or grid of video thumbnails.
2. When a thumbnail is clicked, start playing that video and ensure all other videos stop — only one video plays at a time.
3. Provide a "Play All" control that automatically plays all videos sequentially and stops at the end.
Outline your approach and key decisions (state with hooks, refs to player elements, effect handling, media event listeners). Then address the following follow-ups:
1. How would you optimize performance when the list contains many videos (e.g. virtualization, lazy loading, thumbnail vs. player mounting, memoization, preload strategy)?
2. How would you structure state management for clarity and scalability (lifting state, React Context, reducer patterns, controlled vs. uncontrolled items)?
3. How would you split the component hierarchy and define props/interfaces to improve maintainability and extensibility (e.g. Playlist, VideoItem, Controls)?
4. What accessibility and browser autoplay considerations would you address?
Overview: Build and optimize a video playlist component evaluates requirements, scale assumptions, API/data design, architecture, trade-offs, failure modes, and rollout in a realistic interview setting. A strong answer states assumptions, handles edge cases, explains trade-offs, and shows how to validate the result clearly.