How can i make a introdution video to play at the start of a level

How i make a video to play,when the player starts the game?

Movie Texture

You could use a movie texture if you’re talking about importing a video file into Unity.

If you’re video is something in the game you’re making then I (personally) would just make a level and model/code the animation.

http://docs.unity3d.com/Documentation/Manual/VideoFiles.html

Or, if you don’t have pro and don’t care about app size, fake it with a GUITexture you change the texture of every frame.

Or, search for plugins.