According to an interview with Burns from back in 2004, his least favorite part of filming "Blue's Clues" was the blue screen (via Spin): "Acting on a blue screen is awful ... Ask Ewan McGregor — and he had dwarves and whatnot to act with ... I was at a place where I do this forever and make this who I am, or I do a whole bunch of other exciting stuff."
Per Shutterstock, blue screen technique is among the most common types of scene setting when filming, and is also known as chroma key. The actors — or, in this case, actor — perform in front of the blue screen, which is replaced by other appropriate visuals during the editing process. "Blue's Clues" is notable for its use of cutout animation and mix of animation and live-action filming — of course, Burns and the other hosts spent most of their time on the show talking to animated characters, which must have been something of a challenge. It's unsurprising that acting on a blue screen was his least favorite part of making the show.
