Ok, time for detective work.
Did you solder all connections like in the Utube video?
Are you powering the sound detector and Arduino from a separate power source, like the video?
If you place a piece of black electrical tape over the microphone opening, do you still get the same random results?
Are you testing in a noise filled environment, such as music or TV playing, or kids playing or street noises?
Earlier you mentioned the analog values indicated when you were closer to the mike. Were you making noise at that time? What was happening that caused the change in values?
Paul