There are a lot of ways, you can prevent a bot from accessing the game or pretending to be a user. Something as simple as a video must be important for both the users playing the game or you run your game into an Iframe with secure inputs or dynamic html tag names to prevent it from bots.
All meaningless. Even if you come up with a system which will 100% prevent bots from playing (which is not possible), I could simply open a second window or even set up a second machine out of shot of the video, copy all my opponent's moves against a computer program, and then simply mirror the move the computer makes against my real opponent.