Dennis Miller on The Daily Show

Today I watched a recent video of Dennis Miller on The Daily Show and noted how similar it was to a previous visit I'd seen. Both times, Miller totally slays not just the audience but also John Stewart, who can barely stay on his chair he's laughing so hard. What's strange about this is that Miller isn't close to being funny in any other appearances on other shows, unless you count the laughably unfunny CNBC show. Could Jon Stewart be providing him material for the Daily Show appearances? Or maybe Jon feels like he owes Dennis for the way Daily Show is similar in style to Dennis' run on Weekend Update? Or maybe Dennis is blackmailing Jon? Why does Stewart make Miller funny?

(for the record, I never liked Miller on Weekend Update, it was too much attitude for me)