I have seen a opening From youtube in my last game. I play accordingly. Game says i am cheating

Hello.. i have seen a gautam chess video and play accordingly in my last game. Exect moves he teach in youtube. Game is stopped and says i am cheating and i loose.. why is this so..
Shared video link also
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youtu.be/hLFSufXxtuI

Please see lichess.org/appeal