    <!--
                Copyright: Copyright 1998-2001 W3C (MIT, INRIA, Keio), All Rights Reserved.
    See http://www.w3.org/Consortium/Legal/.
    Author: Aaron Cohen (Intel), Jeff Boston (IBM)
               Version: May 1, 2001
                Module: Timing and Synchronization
               Feature: Negative begin times
             File Name: simple_negative_begin.smil
      Media Components: 2 QT
     Expected Behavior: at t=5  video2 appears.
                              at t=10 video1 appears 5 seconds into the video.
                              at t=15 video1 and video2 disappear.
    -->
    <smil xmlns="http://www.w3.org/2001/SMIL20/Language">
    <body>
            <par>
                    <par begin="10s">
                            <video id="video1" begin="-5s" dur="10s"
    src="../videos/nasa.qt"/>
                    </par>
                    <video id="video2" begin="video1.begin" dur="10s"
    src="../videos/nasa.qt"/>
            </par>
    </body>
    </smil>