TV2 said police confirmed that Breivik confessed to publishing the material, appearing on Friday.
The video advocates for fighting against cultural Marxism and Islamism.
The document describes the bombing as a martyrdom operation.
The video, which contains the name Andrew Berwick is entitled 2083 - A European Declaration of Independence.
The accompanying document, which is more than 1,500 pages long extolls his political views and contains what appears to be a self-reported detailed account of his activities in the months before the bombing until July 22, the day the operation was to take place.