I want to make a script that plays a song from YouTube, so can somebody help me with that?

I want my place to be able to bring up a GUI that can play this song. I don't want it to play automatically, but I want a button that says "Play Song" that can play the song.

You can't get a song from youtube playing in your place. The only way to add your music is upload a sound to ROBLOX for 100 R$. (<Too much) Then, you have to get a sound from basic objects. Put this is the soundID of the sound: 'http://www.roblox.com/asset/?id=(ID here)' Then you can create a GUI button script for exemple:

script.Parent.MouseButton1Click(function()
	script.Disabled = true -- Disables the script
	local sound = script.Parent.Parent.Music -- Exemple of your sound location
	sound:Play()
	wait(10) -- Exemple time
	sound:Stop() -- Sound stops
	script.Disabled = false -- Re-enables the script
end)

Remember, this is an exemple. You can do this different.

Linking songs or sound/videos from youtube is not available yet. Try buying audio for it, 120 seconds of it.

You have to go to a MP3 file maker website. You simply put in the link of the audio from Youtube you want, then it will generate a MP3 file. From there you have to buy the audio on ROBLOX for 100 R$.

Find a Midi version of it and use this system in your game: http://www.roblox.com/MIDI-Player-8-7-BETA-Better-Instrument-Creation-place?id=189859

(why is that -1 in my answer? it's an alternative option, very good btw)