stupid question: they don't give away valuable stuff for free, why do they expect, no demand, people give them stuff they consider VERY valuable for free? For them to use however they want?

That's a very difficult question to answer. The word "priceless" comes to mind. Take a walk around a museum. Much of the stuff in their cost someone a pretty penny and yet they've donated it both for the public good and to ensure it'll be preserved. What you get in return is knowing that long after you're gone people will still read your name.
How did you put a price on the sound of an extinct bird or frog. No doubt someone would have suffered much hardship and expense making that recording, their expenses are oftently covered out of the public purse or by donation. The bigger question though is the loss to all of us if that is lost.
I've kept backup copies of sacred local native music. Recorded at considerable expense by the Australian Museum. No real commercial value, in a few years it will be priceless though as no amount of money can be expended to replace those sounds.

On the other hand I'm in no hurry to expend many hours of my time using my expensive kit to go out and try to record a kookaburra and get nothing back for my effort. That bird is far from extinction. But if I'd been lucky enough to have my own recording of that sound on file I'd donate it in a heartbeat.

Bob.

I'd happily donate my stuff too, and I'd even happily go out & record audio/video for someone no charge if I thought it would a good enough reason, but this isn't you helping me out or me helping you out, it's people helping out an organization that charges good $$ if we wanted something.

Reading their own submission guidelines, this is a great resource for them: people donate stuff they most likely can't get and they get full unlimited use of it, but the uploaded still has full copyright control for everyone else. So this isn't a free library for others to use as they want, this is a library THEY can use as they want.

Basically, why would any audio/video person want to go out & put time/$$ in to getting "rare" sounds & give (donate is a deceptive term) them to a company so in 10 years they can resell it at 100% profit?

You're right that it is like a museum: those works are owned by someone & you can't even take pictures, you have no rights to anything in there at all. But it's nothing like you're recording the native music: you didn't go out on your own & get that, the place that had value on it payed you to do it because they knew it would be valuable some day (even if not monetarily)

you want kookaburra's? i'll give you kookaburra's:

http://www.mediafire.com/?nzinhztnet2

Clause 7 says what you share with them is under a non exclusive grant of copyright, you do grant them the right to share it with other parties and you do retain the right to use the work yourself.
The Beeb is a NPO.
I cannot see how they could construct a legal contract any other way unless maybe in this instance they should require you to simply place your work into the public domain.

Bob.

Thanks, annoying buggers when you don't want them :)
I'll add cicadas to the list of unwanted audio intruders. Impossible sound to filter out.

Bob.