Not counting stuff like Hannah Montana and the Jonas Brothers flicks, it's been a while since movie musicals produced actual hit singles. It's been several decades since musicals like Grease or (technically) Saturday Night Fever were spinning off smash after smash, and only Disney stuff, and TV musicals like Glee or Nashville, have had such an impact recently. That's why it's so jarring to see so many musical titles in Billboard's Hot 100 this week. You can find an impressive five of them adorning the lower stretches of the charts—three from Pitch Perfect (or Glee: The Movie: The College Years) and two from Les Miserables.

None of the five songs are notable radio hits yet, but all are doing well enough on iTunes and the like to make the Hot 100 pretty much on sales alone, giving non-pop-established actresses like Anna Kendrick and Anne Hathaway their first taste of pop success. Of these five, two are long-beloved showtune classics (Samantha Barks' "On My Own" and Hathaway's "I Dreamed a Dream" from Les Mis) and two are medleys of time-tested pop smashes ("Bellas Finals" and "Riff Off" from Pitch Perfect). But by far the most interesting is Anna Kendrick's "Cups" from Pitch Perfect, a cover of English band Lulu and the Lampshades, known to Kendrick via a popular YouTube version of the song done by Anna Burden.

In the movie, Kendrick uses her rendition of the song as her audition for the Bellas, the a capella group at the center of the movie, while performing an intricate rhythmic routine with a cup on a table as the song's sole percussion. (She would later perform the song in a similar fashion live on David Letterman, and quite impressively.) Listened to separately from the movie, the song is unusual for any number of reasons—not only is it a solo a capella song, which always makes for a stark, minimal listen, but it's a scant 77 seconds long, which would surely make it the song to hit the Hot 100 in quite some time. (Even the original "incomplete" version of Rihanna's "Birthday Cake" from 2011's Talk That Talk ran a second longer than "Cups.")

But despite the preponderance of smash hits covered on the Pitch Perfect soundtrack—"Since U Been Gone," "Party in the USA," "Don't Stop the Music"—it's Kendrick's relatively obscure YouTube cover that's finding the most individual success. The song is #81 on the Hot 100 this week, highest of the three Pitch Perfect entries, and has climbed up to #45 on the iTunes chart, higher even than either of the Les Mis entries—though Oscar season may end up resulting in a bump of one or two of those, especially if Hathaway has anything to say about it.

Why is the song doing so well, despite its unconventional nature? Well, if Glee's pattern of success of recent years has taught anything is that while covers of established hits will always be of minor interest, you hit the home runs with covers of lesser-known songs that people don't necessarily have pre-established ideas about—songs like fun.'s "We Are Young" and Gotye's "Somebody That I Used to Know," both of which Glee helped catapult from obscurity to mega-success and enjoyed very good sales with their versions. Covers of such unknown songs tend to better capture the public's imagination, because there's not an overplayed original fighting for space with them in people's memory, and forcing constant comparison that rarely does the new version any favors.

It also just happens that Anna's "Cups" is quite good. Her voice is lovely and unassuming, and the sparse accompaniment makes it almost sound like an Aphex Twin song come to pop life, while the song's ultra-short runtime assures that its gimmickry never grates or tires. The song is catchy and quirky, fleeting but memorable. It's definitely a song you want to hear more than once, so why not just buy the mp3? It's not a likely breakout hit, but it's not an inexplicable one either. And so far, it's one of our favorites of this brief calendar year.