Syncronized FLV streams

That's what I'd do if I needed to make sure everyone is done viewing a stream. You might even go so far as to have each client report its progress on an interval so the presenter knows how long the slowest client has to go. Might be a little overkill, but I don't know how varied your client's connection speeds will be, or what sort of bitrates you're working with.

Alrighty, thanks for the advice, Jay,

Looks like your solution to monitor the attendees position and start the Q&A when everybody is done is the best solution.

Maybe in a future release.

I know you know your stuff, but are you sure you can't publish() from a SWF which is using a live stream? What I mean is something like this:
var nc = new NetConnection();
nc.connect('rtmp');
var ns = new NetStream(nc);
ns.play('myFLV',0); // stream in the 'recorded' FLV file
ns.publish('yourFLV'); // and publish it back out

Then in the various attendee SWFs I have
ns.play('yourFLV');

But that's all assuming that a single NetStream can both play and publish what its playing at the same time, which I guess it cannot.

Incidentally, the docs say for NetSream.publish that its "sends streaming audio, video, and text messages from the client to the Flash Media Server". So audio is done via attachAudio, video by attachVideo, but how are "text messages" done? Is that referring to NetStream.send()?

Nope... can't be done reliably.

The problem is that you can't guarantee that latency will be consistent amongst all of your clients, and you can't guarantee that everyone will have adequate bandwidth to view the stream completely without rebuffering.

What you might do is add some methods to your SSAS that will notify the presenter when everyone is done viewing the stream. At least that way your presenter will know when everyone is ready for Q&A.