Universality and particularity of contradiction: Zhuang Zedong mentioned in the video that ping-pong diplomacy is a universal historical event, not only between China and the United States, but also an important event for global peace and development. At the same time, ping-pong diplomacy also has its particularity. It is an important exchange between China and the United States during the Cold War, with special historical background and significance.

2. Principal contradiction and secondary contradiction: Zhuang Zedong mentioned in the video that the principal contradiction of ping-pong diplomacy is between China and the United States, and the secondary contradiction is domestic contradiction in China. He emphasized the importance of solving the main contradiction, but also pointed out that solving the minor contradiction also played a positive role in promoting the solution of the main contradiction.

3. Contradictory struggle and reunification: Zhuang Zedong mentioned in the video that the success of ping-pong diplomacy is the victory of the contradiction struggle between China and the United States and the reunification of the two countries. He emphasized the dialectical relationship between contradictory struggle and unity, and pointed out that only by constantly promoting unity in contradictory struggle can peace and development be achieved.

4. Stages and development of contradictions: Zhuang Zedong mentioned in the video that ping-pong diplomacy is an important stage and turning point in the development of Sino-US relations. He emphasized the dialectical relationship between the stages of contradictions and development, and pointed out that only by constantly promoting the development and transformation of contradictions can the long-term stability and development of bilateral relations be realized.