Land raw upload durably
Do not push huge files through the app tier when direct-to-blob upload and resumable transfer exist.
Free YouTube breakdown
How to answer Design YouTube in a system design interview.
Strong answers split YouTube into upload, processing, metadata, origin storage, and delivery. Weak answers talk about “video streaming” as one box.
Center of gravityDelivery architecture after processing.
Upload firstTranscode asyncCDN delivery
The pivot
The product is not a video file. It is a set of streamable renditions.
Transcode asynchronously
Generate multiple renditions and segment them for adaptive bitrate playback.
Push delivery to the CDN
Playback traffic belongs on a delivery plane, not on the core application servers.
Want the full version?
The paid YouTube book goes deeper on upload and delivery tradeoffs.
The full breakdown covers resumable upload, manifests, segment strategy, transcoding workflows, metadata separation, and playback tradeoffs.