nonsense

import operator
from collections import defaultdict

NONSENSE = {
    'SONG_A': 'love you baby much love i you',
    'SONG_B': 'monitors could be the real monitors of the world',
    'SONG_C': 'the world is a big world of worlds on earth, world'
}

def word_detector(songs_data):
    words = defaultdict(dict)
    for value in songs_data.values():
        for word in value.split(' '):
            if words.get(word):
                words[word] += 1
            else:
                words[word] = 1
    return sorted({k:v for k,v in words.items() if v > 1}.items(), key=operator.itemgetter(1))[-5:]

print(word_detector(NONSENSE))