When retiring newsman Carl Kasell entered NPR’s broadcast booth in 1975, his voice went out over airwaves bounced across antennae nationwide to reach radio listeners. When incoming PBS NewsHour staffer Hari Sreenivasan presents his news, he’ll be anchoring video updates connected across digital platforms to bridge the on-air TV show to Web users worldwide. Starting Dec. 7, Sreenivasan will deliver online video news updates on the NewsHour‘s website and anchor the headline summary of each evening’s broadcast edition of the newly retooled program. He comes from a similar spot at ABC News Now, where he anchored the 24-hour online service. Sreenivasan’s reports have appeared regularly on the CBS Evening News, The Early Show and CBS Sunday Morning. He also was a reporter for World News Tonight and Nightline.