I only caught part of the debate, but even in a crowd as hostile as that at the JFK School of Government in Red Square, Dershowitz held his own. He got strident at times (and his voice could cause a hyena to cringe), but he managed to make his points earnestly and cogently, while Commski soft-sold the usual platitudes about Evil America.
And Dershowitz mopped the floor with him in the summations.
The crowd can indeed vary wildly, depending on who is speaking. The Weekly Standard event probably drew few 'typical Cantabridgians.'