Xbox's new bet on advertising could shake up gaming — if players don't revolt

INA FASSBENDER/AFP via Getty Images A version of this post appears in the CMO Insider newsletter. Sign up for Business Insider's weekly marketing newsletter. With little fanfare, Microsoft's Xbox made a move last week that could shake up the gaming ad market. Xbox is testing a way for users to stream games they own for free by watching ads, rather than paying for a Game Pass subscription. There's no word yet on what exact ad formats will be available or which brands will participate. Xbox has…