@[email protected] @[email protected] Having gone through my own reading rabbit-hole on UN diplomacy in the past, I can clarify: The vote was on passing the "important question" scheme that the US first devised in 1961. Every time a motion in the UNGA was put forth to restore the UN seat to China, the US inserted a preliminary amendment to have the motion considered a "important question," which would require a supermajority rather than a simple majority for it to then pass. This blocked China's membership for 10 years until 1971. This is why the vote in the video has the US and its underlings voting in the affirmative and why the Assembly laughed, because by the US' turn to vote, it was already clear that the UNGA majority would reject the supermajority amendment and thus be able to restore China's membership.

The end came abruptly for the Taiwanese delegation. On October 26, 1971, the General Assembly narrowly rejected the “important question” resolution, which would have required a two-thirds majority to replace Taiwan with the Communist government. Anticipating the inevitable next step, the Taiwanese delegation walked out of the General Assembly moments before the lopsided vote that formally evicted them. In that instant, Chiang Kai-shek’s government lost all rights at the United Nations, including the coveted council seat. It was just as well that the Taiwanese had left. Many delegations broke into wild applause—and even dancing—as the results were announced. Finally, after twenty-five years of exclusion. Communist China would be in the inner sanctum.

Bosco, D. 2009. Five to Rule Them All: The UN Security Council and the Making of the Modern World. Oxford.

the eleventh hour american proposal

Not exactly "eleventh hour", it was submitted on the 29th of Sept, 4 days after the Albanian (et al.) proposal on the 25th of Sept. A truely eleventh hour proposal can be seen with the Saudi Arabian A/L.638 submitted on the day of the vote (25 Oct.)

Also... From A/PV.1976:

Mr. MALILE (Albania):
[...]
73. The explanations we have heard here concerning draft resolution A/L.632 are completely unfounded. This draft is basically an integral part of the anti-Chinese attempt of the United States of America to legalize its "two Chinas" plot and is designed to sabotage the approval of the draft resolution of the 23 States, including Albania [referring to A/L.630, which would expel the RoC and invite the PRC. It became the draft that was adopted]. The content of such a draft is illegal. It seeks to open the way to the United States manoeuvre aimed at involving the United Nations in the domestic affairs of the Chinese people, which is the aim of draft resolution A/L.633 [keeping the RoC in the UN, but replacing it with PRC on Security Council]. As has been clearly pointed out, that draft resolution is in flagrant contradiction with Article 18 of the Charter. It goes without saying that the Article cannot be applied to our draft resolution.