In a recent weekly update, bungle said that the most effective way to report someone of your own suspicions is using the in-game report feature. They also stated that posting videos and just saying in the forums that someone is cheating, is very ineffective way and Bungie does nothing about it. The In-game report feature does not work on a single or 3 reports alone. A player must have multiple reports to ensure the player is not following the rules. That is where Bungie steps in to inspect the player and decides whether or not to strike the Ban Hammer.