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Lesson 1 of 16

40. Design Video Upload and Streaming (YouTube)

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The interview prompt
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40.1 What do you ask first?
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40.2 How big is this, really?
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40.3 What are the doors?
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40.4 What do we store?
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40.5 What does the whole system look like?
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40.6 How does the upload pipeline work?
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40.7 How does transcoding work?
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40.8 How does adaptive bitrate work?
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40.9 How does CDN delivery work at this scale?
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40.10 How do you count views?
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40.11 What would you say in the last five minutes?
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Score yourself
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Variations to practise
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Sources
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Code lab
40. Design Video Upload and Streaming (YouTube)

The interview prompt

3 min read+10 XP

This chapter is a full interview round, played out step by step. The interviewer's lines are in quotes. At each step you'll see what a strong candidate says, the pushback the interviewer throws, and how to answer it. At the end, grade yourself with the rubric.

How to use this chapter

  1. Read only the prompt below. Then stop.
  2. Set a 45-minute timer and do the whole round yourself, on paper or a whiteboard, out loud. Use the framework from Chapter 1: READ, then Draw, Dive, Defend.
  3. Then read the walkthrough and compare. Score yourself with the rubric at the end.

Chapter 26 explained how CDNs deliver video segments. This round covers the whole journey: a creator uploads a raw file, the system turns it into something every phone can play, and millions watch it without stalling.

The prompt

"Design a video platform like YouTube: creators upload videos, and viewers anywhere can watch them smoothly on any device."

Stop here. Start your timer.