Why am I getting this error?

Here is the code that I took directly from a flash tutorial off this site.

var nc:NetConnection = new NetConnection();
nc.connect(null);

var ns:NetStream = new NetStream(nc);

theVideo.attachVideo(ns);

ns.play("BEESeq.flv");

But I keep getting this error

1061: Call to a possibly undefined method attachVideo through a reference with static type flash.media:Video.