The full meeting video is here. The Pluto debate and vote starts at 26:10 of the IAU meeting video.: https://www.iau.org/public/videos/detail/iau2006session2/
The IAU President and a small committee clandestinely and materially changed the naming resolution, kept it secret from dissenting members and the press, distributed the proposal just before the vote, rebuffed dissenters and concluded with a show of hands without an official count.
The entire International Astronomical Union session that resulted in the definition that demoted Pluto can be viewed on the video here. The voting discussion relative to Pluto begins at around 26:55 into the session. Most of the descriptive text below about the process was taken directly from the video of the debate and vote proceedings.
The vote was scheduled at the end of a 10 day conference in Prague when almost everyone had left. Only 424 of nearly 10,000 members remained.
IAU President, Ronald d. Ekers, opened the session stating that the IAU was asked to act on the planet definition issue. He stressed that prior proposals were delayed because cultural and popular issues needed to be considered.
Ekers stated that this was not just a scientific debate and that the issue cannot be resolved by science alone. "This is not just a scientific issue of what is correct. There is no correct answer to this question."
"The question is; what is a sensible compromise that will not just work for the professionals in the field but will work for everybody who is interested the sky, the planets, is curious, is educating and so on."
After Mr. Ekers and a panel member read two overwhelmingly positive and zero dissenting messages from colleagues on the pending resolutions he called for a show of hands however; 15 IAU members stepped forward to speak. The first 14 speakers were dissenting, and generally cut off by Mr. Ekers. The contentious and angry dissention included voters "not being properly consulted" and receiving the changed resolutions "just now as entering the session."
The response from Ekers; "the last step of the proposals was done in secret to keep them from the press." It seems that a lot of people were interested in this outcome and were getting in the way of the desired outcome of the rogue scientists.
These IAU members strongly dissented stating that the decision to vote was rushed, more debate needs to take place, the vote should be postponed and that "what was being presented was an insult to the entire astronomical institution."
The 15th and final speaker was recognized and stated that he was no scientist but that he wanted to say that the committee was doing a great job.
A movement by prominent scientists to meet mid-2007 to organize an electronic vote by the full membership did not succeed.
Think back to when you were a kid and how fascinating it was to gaze into the starry sky at night. School kids all over the world feel this way. Students in Clyde Tombaugh's (the person who discovered Pluto when he was 24 years-old) home town have twice used letter writing campaigns to save Pluto's planetary status. Taking Pluto away confused and saddened children, where adding could have caused expanding wonderment.
Neil deGrasse Tyson, Chairman of the Board of Directors of the Planetary Society in an opinion written for Natural History Magazine stated that, in his planetarium shows of the solar system to over 10,000 junior high school students, Pluto was the overwhelming favorite among the 9 planets. "They consistently cheered the loudest for Pluto, especially when I recited the planets in sequence, aided by the time-honored mnemonic My Very Educated Mother Just Served Us Nine Pizzas."
Tyson also stated on Comedy Central's Stephen Colbert Show that he never wanted to "kick Pluto out of the solar system." However; Mr. Tyson now supports the demotion.
So much for time honored.
97-Year-Old Widow of Pluto Discoverer "Shook up"
Patricia Tombaugh was quoted in the nations newspapers as being "shook up" by the demotion news. She said that her husband Clyde resisted earlier attempts to demote the planet and she, despite her age, shortly after Pluto's demotion, reportedly took part in a demonstration against the demotion.
Ms. Tombaugh personally attended the launch of the New Horizons Mission. The space probe, containing ashes from Clyde Tombaugh, just completed its flyby of Pluto in July of 2015.