Leon Trotsky, “Vodka, the Church, and the Cinema” 12 July, 1923:

The most important weapon in this respect, a weapon excelling any other, is at present the cinema. This amazing spectacular innovation has cut into human life with a successful rapidity never experienced in the past. In the daily life of capitalist towns, the cinema has become just such an integral part of life as the bath, the beer-hall, the church, and other indispensable institutions, commendable and otherwise. The passion for the cinema is rooted in the desire for distraction, the desire to see something new and improbable, to laugh and to cry, not at your own, but at other people’s misfortunes. The cinema satisfies these demands in a very direct, visual, picturesque, and vital way, requiring nothing from the audience; it does not even require them to be literate. That is why the audience bears such a grateful love to the cinema, that inexhaustible fount of impressions and emotions. This provides a point, and not merely a point, but a huge square, for the application of our socialist educational energies.
The fact that we have so far, ie., in nearly six years, not taken possession of the cinema shows how slow and uneducated we are, not to say, frankly, stupid. This weapon, which cries out to be used, is the best instrument for propaganda, technical, educational, and industrial propaganda, propaganda against alcohol, propaganda for sanitation, political propaganda, any kind of propaganda you please, a propaganda which is accessible to everyone, which is attractive, which cuts into the memory and may be made a possible source of revenue.

Lenin in a conversation with A.V.Lunacharsky, April 1919:

You are known among us as a protector of the arts so you must remember that, of all the arts, for us the cinema is the most important.

Cinema was a new invention in the age of Lenin and Trotsky, but the Bolsheviks were quick to understand the need to visualize dissent. Today, YouTube and similar online platforms, can provide a venue for revolutionary movements to spread their propaganda and agitation visually to a much wider audience.