I think you can process the approx time using watch on
Stream.onPlayStatus (http://help.adobe.com/en_US/flashmediaserver/ssaslr/WS5b3ccc516d4fbf351e63e3d11a11afc95e-7 e42SSASLR.html#WSba58fdee7d6ee05f-3e4c639a126965313a2-8000) which will trigger with NetStream.Play.Switch when stream switches. Find Stream.time at that time ( say startTime of current video).
Find Stream.time of playlist (say total time).
Current video play time = total stream time - start time of current video.