Very slightly off thread.

Yesterday I was an extra in a Madd Damon movie being shot in NYC. His part was as a politician. The person introducing him to the "audience" did his speech out loud when they were recording. Later, when they were only doing different angles and visuals, he "synced" to himself so that his timing was right for his movements. A really beautiful job, especially as it was his first job as a member of the Screen Actor's Guild.