I wish I could have been there.
My uni career was filled with frustration with overconfident students sending perfectly good lectures off on tangents. The worst was that when I attempted my own non-sequitur inquiries the result was rolling eyes and a pained silence only broken by "Are there any more questions before we get on with this topic?"
(the other guy not the one that gave you coochie warts, Sun 9 Dec 2012, 16:31, 1 reply)

To be fair, it's one of the things that goes with the turf
We can't fault people for wanting to get involved, but as you say when it derails the topic you have to be careful. I would only try a trick like this with someone I know wouldn't be discouraged by it; if one of the people who are generally quieter started a tangent I'd be more than happy to let them get on with it!
(Although personal opinion = // = theoretical debate *shudder* )
(Sivvus trolley collision in the fruit aisle led to a jam, Sun 9 Dec 2012, 16:43, closed)