The plasma was actually an upgrade. From the 1960's until a few years ago, the screen up above the juice bar used a scopotone type movie machine that played the 4 minute Dole film on a movie screen. It could be hard to see however, and time wasn't kind to the old equipment from Walt's era. A few years ago the original 1960's film was digitially remastered and they fit a plasma screen in the space that once was a small movie screen.
The 1960's film is called "The Flavor Of Hawaii" and it's Disneyland history and quite famous, and many fans will wait to enter the pre-show lanai until after the theater is loaded so they can make sure they see the movie because it's so kitschy and beloved.
The Dole preshow film amongst the thatched roof may not translate well to 21st century WDW audiences, but at Disneyland it's part of the magic of the show. For those curious about a piece of Walt-era Tiki Room kitsch, here's the YouTube video of the little movie that plays every 20 minutes above the juice bar.
http://www.youtube.com/watch?v=LMGkPeJV3jo&playnext=1&list=PL1D7707C6CEF3035A
"The golden cylinders are then inspected and trimmed." -The Flavor Of Hawaii pre-show film :lol: