[C#][XML] Problem mit XmlNode.Attributes[]

<?xml version="1.0" encoding="utf-8" ?>
<playlist>
    <video source="hi">Hallo</video>
</playlist>

public IEnumerable<Video> GetVideos()
{
    XmlNodeList Videos = Config.SelectNodes("/playlist");
 
    foreach (XmlNode N in Videos)
        yield return new Video(N.InnerText, N.Attributes["source"].Value, "", 0);
}