Connect the power cord to you computer then to your phone.. once connected, you computer should recognize your device which an icon of your device would be located within the file management screen. (assuming your op sys is win10)
From here, access the phones settings which would show you the internal and external drives located within your phone. The internal drive or folder are that which (by default) all data is saved or transfered to. But if you have a MicroSD card, (external drive or storage) this could be where your video is located. This may mean exploring (but do not alter any of the folder except to remove or transfer data and images to and from your computer & smart phone)
One key point here, would be that if your device is not recognized when connected to you computer, you may have to adjust the phones power charging setting as to allow for data transfer. typically this is done when you first connect your phone to the computer.
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