I saw Dittleman. He presented it very well--an excellent showman--but most of what he did wasn't too difficult to figure out.
When he did "Let's Make A Deal", it was clear that every case had a double panel--one for "this is your case", and one for "no deal". The girls just opened the "no deal" one, and when he revealed the "this is your case" one, he opened the other panel. Similarly, when he pulled out the card of "The correct case is #4", or whatever it was, he just pulled out the correct card out of a stack of 16.
Similarly when he had Howard color his drawing--there were a limited number of color combinations he could have done, so he just chose the correct one out of a stack to reveal.
When he did the "trick" where he told everyone in the audience to picture a shape, "like a square, but not a square", and then to "picture a second shape around it", that's just knowing human nature on such assignments. Given that particular wording (emphasis on "like a square, but not a square", and on the word "around"), and the short response time required, most people will naturally picture a circle around a triangle, with the second most common being a triangle around a circle. It's kind of like when someone 'quotes' someone by saying that "he said a four letter word which I can't repeat, but it starts in 'f', ends in 'k', and isn't 'fork' or 'firetruck'", everyone's minds comes to the same conclusion of what he's talking about.
I forget what else he did--but they were all equally explainable. But very well presented nonetheless.