List all videos modified since a certain date.

def find_modified(since, filter_list=None, _connection=None, page_size=25,
        page_number=0, sort_by=enums.DEFAULT_SORT_BY,
        sort_order=enums.DEFAULT_SORT_ORDER):
        """
        List all videos modified since a certain date.
        """
        filters = []
        if filter_list is not None:
            filters = filter_list
        if not isinstance(since, datetime):
            msg = 'The parameter "since" must be a datetime object.'
            raise exceptions.PyBrightcoveError(msg)
        fdate = int(since.strftime("%s")) / 60  ## Minutes since UNIX time
        return connection.ItemResultSet('find_modified_videos',
            Video, _connection, page_size, page_number, sort_by, sort_order,
            from_date=fdate, filter=filters)