Ok so i am making a simulation style game where a player clicks a button on the screen and it plays a certain video, moving him forward, and then i want the video to freeze frame until he presses the forward button again, playing the next clip. I am fairly new to unity so where would i begin to start when doing this? I was thinking about making a canvas and adding a GUI button and then adding MovTexture.Play function if the button is clicked, although, i still have no idea to start with coding, any more questions, feel free to ask. 
Since you are familiar with MovTexture, you can start the coding by adding a List OR a Dictionary for your videos (as GameObjects), then let your buttons manibulate the Play, Pause & Stop public functions of your MovTexture as well as the reference to the required gameobject
I’m not sure if I’m understanding this right, but a stack could work as well.