By Marina Lopes NEW YORK (Reuters) – ATT Inc said Tuesday it would partner with The Chernin Group media holding company to invest $500 million in a joint venture for web-based video services, making it the latest company aiming to tap the growing consumer demand for online video. The move follows announcements by Verizon Communications, Disney and Dish Network Corp which have plans to roll out video products outside a traditional TV subscription. Chernin Group, former News Corp president Peter Chernins holding company, produces films and TV shows, and has a stake in Crunchyroll, a subscription and video-on-demand service. ATTs massive reach on those platforms across mobile and broadband and their commitment to the online video space make them the perfect fit for this venture with us, Chernin said.