Warner Bros screened a 2 1/2-minute trailer of its long-gestating Jungle Book adaptation Mowgli (formally titled Jungle Book: Origins) this evening at CinemaCon in Las Vegas. Director Andy Serkis along with stars Cate Blanchett, Benedict Cumberbatch, Matthew Rhys and Rohan Chand were present to cue up the video for the film, which began principal photography in 2015. Serkis said his take on the Rudyard Kipling classic focuses on “the journey of Mowgli of being an…