Select a song from VLC and run this Applescript to Add a song to iTunes, Trash it from its original location, and then removing it from the VLC Playlist. It has only been tested for a single song selection but can accomodate playlists of any size.

AddiTunesTrashFromVLC.scpt

global songAdded
global songDeleted
global selectedSong
global safetyCheck

# This variable is used as a boolean to see if a file has been added to iTunes or not
set songAdded to false
# This variable is used as a boolean to see if a file has been deleted or not
set songDeleted to false
# This variable is used to store the alias location of the song to be deleted / added
set selectedSong to false
# This variable is used to track whether we've attempted a safe workaround to deleting a current song
set safetyCheck to false

getSong()
addSong(selectedSong)
deleteSong(selectedSong)
finishUp()

on getSong()
	# Reveal selected song from the VLC playlist in the Finder
	tell application "VLC"
		activate
		try
			tell application "System Events" to keystroke "r" using {shift down, command down}
		end try
	end tell
	
	# save the selected song
	if is_active("Finder", true) is true then
		tell application "Finder"
			set selectedSong to (get selection as alias)
		end tell
	end if
end getSong

# Add Song to iTunes Library
on addSong(selectedSong)
	# Bail out if there's no saved selected song
	if selectedSong is not false then
		tell application "iTunes"
			launch
		end tell
		
		if is_running("iTunes", true) is true then
			try
				tell application "iTunes"
					add selectedSong to playlist "Music" of source "Library"
					set songAdded to true
				end tell
			end try
		end if
	end if
end addSong

# Trash the song from the Finder
on deleteSong(selectedSong)
	# Only continue if there is a selected song that has been properly saved and that we've already added it to iTunes
	if selectedSong is not false and songAdded is true then
		# Only delete the file if the file is safe to delete (Not currently Playing)
		if safeSongCheck(selectedSong) is true then
			try
				# Delete the Selected file
				tell application "Finder" to delete selectedSong
				delay 0.1
				set songDeleted to true
			end try
		else
			attemptSafety()
		end if
	end if
end deleteSong

on finishUp()
	tell application "Finder" to close window 1
	tell application "VLC" to activate
	
	# Delete the selected song from the playlist if it has been deleted
	if songDeleted is true then
		if is_active("VLC", true) is true then
			try
				# Press Delete Key
				tell application "System Events" to key code 51
				delay 0.1
				
				if safetyCheck is true then
					ignoring application responses
						tell application "VLC"
							play
							delay 0.1
						end tell
						
						try
							tell application "System Events"
								tell its application process "VLC"
									tell its window "Open Source"
										click button "Cancel"
									end tell
								end tell
							end tell
						end try
					end ignoring
				end if
			end try
		end if
	end if
end finishUp

on safeSongCheck(selection)
	set currentSongPath to currentSongPath()
	try
		tell application "Finder"
			# If it is currently Playing the song, it is NOT safe.
			# If the Path of the currently playing song in VLC (which is a POSIX Path)
			# matches the POSIX path of the selection, it is NOT safe.
			if POSIX path of selection is currentSongPath then
				return false
			else
				return true
			end if
		end tell
	end try
end safeSongCheck

on attemptSafety()
	if songDeleted is false then
		# Can't delete a currently playing song
		# Try and switch songs and select the previous song we tried to delete
		tell application "VLC" to activate
		if safetyCheck is false then
			try
				tell application "VLC" to stop
				delay 0.1
				set safetyCheck to true
				deleteSong(selectedSong)
			end try
		end if
	end if
end attemptSafety

# Utility functions
# Return the path of current playing song otherwise return false
on currentSongPath()
	tell application "VLC"
		try
			if playing then
				return path of current item
			else
				return false
			end if
		end try
	end tell
end currentSongPath

on is_running(appName, waitBoolean)
	tell application "System Events"
		set appRunning to (name of processes) contains appName
		
		if waitBoolean is true then
			# Wait for the App to start running
			set wait to 0
			repeat until appRunning is true or wait is greater than 8
				set appRunning to (name of processes) contains appName
				set wait to wait + 0.1
				delay 0.1
			end repeat
		end if
		
		return appRunning
	end tell
end is_running

on is_active(appName, waitBoolean)
	tell application "System Events"
		set activeApp to (name of first application process whose frontmost is true) contains appName
		
		if waitBoolean is true then
			# Wait for the App to become active
			set wait to 0
			repeat until activeApp is true or wait is greater than 2
				set activeApp to (name of first application process whose frontmost is true) contains appName
				set wait to wait + 0.1
				delay 0.1
			end repeat
		end if
		
		return activeApp
	end tell
end is_active