Blockstream CEO Adam Back has criticized the documentary "Who Is Nakamoto?" for its theory that Bitcoin's creator, Satoshi Nakamoto, was a collaboration between Hal Finney and Len Sassaman. Back argues that time zone discrepancies undermine the film's hypothesis. He points out that during Bitcoin's development, Sassaman was in Belgium, and the timing of Satoshi's forum posts does not align with Sassaman's schedule. Additionally, Back notes that Finney's activities, such as running a marathon while Satoshi was active online, further challenge the theory of their joint authorship. Despite Back's objections, the documentary has garnered support from other industry figures. Coinbase CEO Brian Armstrong and entrepreneur Mark Cuban have praised the film for its thorough investigation into the mystery of Nakamoto's identity.