Brian Steinberg Senior TV EditorDavid Zaslav will lead a new combination of WarnerMedia and Discovery, the latest example of consolidation in the media and entertainment industry as the rise of video streaming continues to upend the entire sector.Zaslav was named CEO of the new company Monday, part of a surprising move by AT&T and Discovery to pool their media resources and make a bid to compete more directly with large rivals like Netflix, Walt Disney and NBCUniversal.