This teaser is from the Chinese movie "Tunnel Warfare" made in 1960s. Yes, the original classification of this movie is "educational", i.e. for teaching purpose in military academies. It was then used to teach the general people how to conduct guerilla warfare if China is invaded (guerilla warfare is in essence "People's War", so it is meaningless if it was taught to the army but not he public). The movie was so well made, with a very good plot as the backbone (apparently based on the trure story about the people in a small village in Hebei, North China called Ranzhuang and Jiaohuzhuang against the Japanese occupation around early 1940s), that it is now still widely remembered and regarded as a classic of the time.
Here is the lyric of the theme song
- The last lines said, "Everybody is a soldier, everybody participate in the war, until the invaders are totally annihilated." Of course, the prerequisite for such People's War is that everybody in the "People" is with you. You need "help" from the invaders to achieve this.
- The Mao quote on the screenshot said, "Revolutionary war is a war by the mass, only by mobilizing the mass can a war be executed, only by relying on the mass can we proceed to war..."
以军遭遇地道战 真主党藏兵于民开展人民战争 (I think the reference on Tunnel is exaggerated, but People's War it is.
Appendix: tactics of tunnel warfare
Screenshot from the movie: illustration of how to construct tunnel (that could defeat smoke, water, and defensible with primitive weapon such as a lance)...
...and how to launch attack using the tunnel infrastructure.