Back in February, before "Frozen" won an Oscar and became the biggest animated film ever, some of the cast members did a live concert where they sang songs form the movie.  There hasn't been much footage of it until recently, but it's getting a ton of attention because the movie won an Oscar...and it's awesome.

Kristen Bell voices the part of "Anna" in the movie, and sings the songs as a result.  However, she didn't do the younger versions of Anna in the movie.  In this clip she actually sings the toddler and teenage part of "Do You Want To Build A Snowman" and she KILLS IT!