Call of Duty Warzone already has in-game video. When you’re dead, you watch your teammate play until they can revive you. You see through their eyes and can talk to them.
in csgo one was able to watch almost anybody playing. Waiting for your friends to finish their match? Just watch without any hassle. Want to spectate one of your random friends? Sure. Sadly the feature has been completely absent since the publishing of cs2.