def return_videos(self, begtime, endtime):
        """It returns the videos and beginning and end time of the video
        segment. The MFF video format is not well documented. As far as I can
        see, the manual 20150805 says that there might be multiple .mp4 files
        but I only see one .mov file (and no way to specify which video file to
        read). In addition, there is a file "po_videoSyncups.xml" which seems
        to contain some time information, but the sampleTime does not start at
        zero, but at a large number. I don't know how to use the info in
        po_videoSyncups.xml.

        Parameters
        ----------
        begtime : float
            start time of the period of interest
        endtime : float
            end time of the period of interest

        Returns
        -------
        list of one path
            list with only one element
        float
            start time of the video
        float
            end time of the video
        """
        try:
            self._orig['po_videoSyncups']
        except KeyError:
            raise OSError('No po_videoSyncups.xml in folder to sync videos')

        if not self._videos:
            raise OSError('No mp4 video files')

        mp4_file = self._videos[:1]  # make clear we only use the first video

        return mp4_file, begtime, endtime