As I spent hours to make it finally work, here my working solution:

    my $ua  = LWP::UserAgent->new();
    my $url = "http://your_url";
    my $filename = "d:\\clips\\videoclip.mp4";

    my $response = $ua->post($url,
        ['file' => [ $filename ]],
        'Content_Type' => 'form-data'  # add here more header paramete
+rs if necessary
    );
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