Systems and methods for synchronization of session content are provided. Session video of a plurality of game sessions may be captured at a content synchronization server. Each captured session video of each game session may be associated with an identifier of the respective game session. Additional content may be sent over a communication network to the content synchronization server. Such additional content may be external to the game session and identified as being associated with a game session identifier. One of the captured session videos may be identified as being associated with a game session identifier that matches the game session identifier associated with the received external content. The received external content may be synchronized to the identified session video based on the matching game session identifiers. A composite video may be generated that includes the received external content synchronized to the identified session video.