You need sufficient altitude or sufficient forward speed to auto-rotate, this had the former but regardless a helicopter doesn't drop like this if rotors are in any way still spinning, could be blades were locked up(possibly one blade missing but it still wouldn't drop like this), which suggest something major mechanical be it deliberate or accidental(to be honest it almost looks like it is being driven into the ground...)

You need sufficient altitude or sufficient forward speed to auto-rotate, this had the former but regardless a helicopter doesn't drop like this if rotors are in any way still spinning, by the look of it it almost looks like blades were locked up, which suggest something major mechanical be it deliberate or accidental..