Activision has released a teaser trailer for the upcoming Call of Duty: Modern Warfare 4 first beta weekend, and it looks pretty great. The trailer shows off some of the content in the beta, and that includes, for the first time in the franchise’s history, a slice of the game’s single-player campaign. The first beta runs April 21-25, and it’s available for those who preorder the game on PS5, Xbox Series X|S, and PC. The beta allows players to try…