Get File Object from wp.Uploader

You can’t hook it directly as wp.Uploader doesn’t expose it but you can use its init() to hook its internal pluploader instance:

add_action( 'admin_print_footer_scripts', function () {
    ?>
    <script type="text/javascript">
    (function ($) {
        if (typeof wp.Uploader === 'function') {
            $.extend( wp.Uploader.prototype, {
                init : function() { // plupload 'PostInit'
                    this.uploader.bind('BeforeUpload', function(file) {
                        console.log('BeforeUpload file=%o', file);
                    });
                },
                success : function( file_attachment ) { // plupload 'FileUploaded'
                    console.log( file_attachment );
                }
            });
        }
    })(jQuery);
    </script>
    <?php
}, 100 );