I've never personally had a problem with audio captures myself, but then again I have some very good headphones.
Visual captures however are a big no no as far as I'm concerned, I fully agree with whoever said they don't work (I've tried solona, and that really didn't work at all).
As for invitation only, the problem is we've had a lot of legitimate new members only, and personally invitation only always strikes me as hugely unfriendly, especially if someone is a litle shy of asking.
Myself, I don't know if I'd have registered on this forum back in 2005 if it'd been invitation only, sinse I don't believe I'd have wanted to ask for an invite, sinse I wasn't really interested enough in audiogames at that stage to want to bother with a complex process like asking for an invite, ---- and what about all those devs or researchers we get?
I like the maths question idea, lords of lords uses a system like that for their registration where your asked a symple question such as what is 4 pluss 6, or what is 2 times 9.
I'm not sure though if spambots could get around that one, but if not it'd be probably nicer even than a generic question about the front page.
I'm afraid I have to disagree Cx2 on levels of spam though, sinse we do seem to have been getting more bots than usual recently, and failing trol employment, some method of tightening registration would probably be an idea.
while I really don't like moving to captures, sinse visual captures are very inaccessible much of the time and audio captures can cause problems for some people, some sort of system might be a good idea.
With our dreaming and singing, Ceaseless and sorrowless we! The glory about us clinging Of the glorious futures we see,
Our souls with high music ringing; O men! It must ever be
That we dwell in our dreaming and singing, A little apart from ye. (Arthur O'Shaughnessy 1873.)