AI & Technical question
How will you design an algorithm for "continue watching segment" for a streaming services platform?
- AI & Technical
- Hard
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What this question tests
System design thinking for a recommendation and state-tracking feature, and how to measure whether it actually works.
How to approach it
- Clarify this covers both resuming a specific episode and surfacing which show to continue in a row.
- Define inputs: last watched timestamp per title, completion percent, recency, and device used.
- Propose the simple core: store last playback position per user-title pair and resume within a few seconds of where they left off.
- Rank the 'Continue Watching' row with recency-weighted decay, demoting or removing titles once fully completed.
- Handle edge cases: multiple profiles per account, cross-device sync latency, and titles removed from the catalog.
- Define success as resume accuracy and row click-through rate.
What a strong answer includes
- Separates storage and sync, an infra problem needing low-latency writes on pause or seek, from ranking, a product weighting problem.
- Gives a concrete edge case most miss: a user 95% through should probably be marked watched, not continue.
- Proposes a measurable quality proxy: percent of resumes that don't require rewinding or fast-forwarding.
Common mistakes
- Jumping to a complex ML model when a simple recency-plus-completion heuristic solves most of the problem.
- Ignoring cross-device sync latency, a common real failure mode.
Likely follow-up questions
- How do you handle a user who rewatches an old, completed show?
- How would you A/B test a change to this ranking?
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Learn the skill behind it
Chapters of the AI PM course that teach what this question tests.
- Chapter 1: Foundations: the model and the decisions it forces on you
- Chapter 8: Evals: define good and make the number defensible
- Chapter 6: Agents and agentic architecture