Commentator (noun)

1. A person who provides spoken or written explanations or analysis of a text or event.
2. A person who provides a series of explanations or annotations of a text or event.

Origin:

From the latin word "commentator" meaning "one who comments".

Examples:

1. The commentator provided a detailed analysis of the game's strategies and tactics.
2. The book includes a commentary by the author on his life and work.
3. He wrote a commentary on the Bible as a commentator.
4. The film's commentary track featured the director as commentator discussing the making of the movie.
5. Many believe that the commentator on the text was more interesting than the text itself.