From Halopedia, the Halo wiki
The video takes the form of File:CHELAN_20200303, a file part of Director Schaefer's "content series" in ONI Section 2's public awareness campaign regarding the UNSC's role in colonial security. Aimed at educating UEG citizens on the history, evolution, and application of the Spartan Program.
ONI Screen activates, showing the file name "File:CHELAN_20200303", and a wave form of a "Comms Officer". With the words "Transmission suspended" in the center of the screen.
ONI Screen deactivates, and the Halo: Combat Evolved Anniversary logo appears saying "Available now" below it.
The filename is a reference to Halo: Combat Evolved Anniversary's launch on the PC and Steam version of Halo: The Master Chief Collection with the number "20200303" referring to the game's launch date of March 3, 2020. The CHELAN part of the name refers to the Chelan app that requests permission when the player logs into Xbox Live through Steam. The number below LINK "20011511" is a reference to the original Halo: Combat Evolved release date on November 15, 2001.