Offline playback is downloading protected content for viewing without a connection — "download to go." It is a marquee feature for mobile (commutes, flights) but introduces a hard problem: the content leaves the controlled streaming path and sits on the device, so it must be governed by an offline DRM license with its own rules.
The mechanics differ from streaming. Segments are downloaded and stored encrypted; the platform issues a persistent (offline) license that lives on the device and carries its own policy — an expiry window (e.g. 30 days to start, 48 hours after first play for a rental), a device binding, and limits on how many titles or devices. The player must enforce that policy locally, including when the clock cannot be trusted and the license eventually expires.
Beyond DRM, offline raises storage management (quality choice, eviction), download resumption, and entitlement reconciliation when the device reconnects. It intersects directly with rental/TVOD windows and rights, making it one of the more contract-sensitive client features.
