A video may not play due to an unsupported format when the media player (software or hardware) doesn't recognize the video file's specific structure or encoding method. Videos consist of two main elements: a container (like MP4, AVI, or MKV) holding audio and video streams, and codecs (like H.264, VP9, or HEVC) that compress/decompress these streams. If the player lacks support for either the container or the required video/audio codec inside it, playback fails. This differs from playback issues caused by network problems or corrupted files, which involve delivery or data integrity.

Unsupported formats are a frequent issue with web browsers playing specific video files directly (e.g., Safari often won't play MKV files without specific plugins), or older media players encountering modern codecs. Similarly, a video recorded in HEVC format (common on newer smartphones) might not play on an older smart TV without HEVC support. Smartphones might also fail to play older format files like FLV. Compatibility varies widely across platforms like VLC, Windows Media Player, embedded web players, or streaming services.

The primary advantage of diverse formats is efficient compression and quality optimization. However, key limitations include fragmentation causing user frustration and device incompatibility. This necessitates conversion tools or installing compatible players like VLC, which supports a vast range. Ethically, lack of support for open, royalty-free codecs like AV1 can hinder accessibility and increase costs, while patent-encumbered formats may restrict usage rights. Future-proofing involves industry shifts towards widely adopted standards like H.264 for broad compatibility and newer codecs like AV1 for efficiency.