I ended up using your solution, though there were a few additional steps I had to discover by experiment with to make it work.
In case iWork '11 doesn't make this easier in the future, I will list the missing pieces here to help others.
I selected all my slides and with the Inspector, used the following "Transition tab" settings: Effect, Dissolve, Duration 1:00 s; Start Transition Automatically, Delay 0.0s.
Again using the Inspectior, this time the "Document" settings for the presentation, I set Presentation to "Self-playing", Delay Transitions 0.5 s, Builds, 2.0s (although I had no builds) and Slide size to 1024x768, since I was using this with a projector.
When I Exported the movie to QuickTime, I set the "Playback Uses" to "Manual Advance" - this is very important! And Formats to "Full Quality, Large". The Audio box was checked or unchecked, depending on whether the movie needed sound or not.
My goal was to play the resulting QT files using my iPad. Oddly enough, I couldn't use Apple's own iPad Video app to do this, but GoodReader app handled the QT movie files just fine. (Go figure!)
The results were very good and my presentation went well. I just wish it would have been possible to do this all with the Keynote program&app on the Mac and iPad. Hopefully, when iWork '11 comes out ...
I should also note that although the above settings work great when the KN presentation is exported to a QT movie, they don't allow the KN presentation to play normally inside KN itself. Each slide with a movie in it will only play for about a second in KN using these settings. But the exported QT movie will play the whole movie on each slide, and then move to the next slide without user intervention and without the need to calculate or enter the duration of the video segments in each slide.