Music Demi Lovato Sings 'Let It Go' in Show-Stopping Live Performance By Antoinette Bueno 2:04 PM PST, December 10, 2014 YouTube Does it get any better than Demi Lovato singing Frozen's "Let It Go?"The 22-year-old belted out the now classic Disney tune at the annual Royal Variety Performance in London last month, though the footage only became available earlier this week.NEWS: Everything 'Frozen' That Happened in 2014Technically, the song isn't a cover, as Demi actually recorded an official version of the song for the film's soundtrack.But perhaps even more notable than Demi's predictably stellar vocals in the performance, is her show-stopping Ashi mullet-hem dress, which was adorned with feathers and a sparkly belt. View this post on InstagramMy Ashi gown I'm wearing at tonight's Royal Variety... I loooove this dress!!! Ironically it makes me feel like a princess... 🇬🇧🇬🇧🇬🇧❤️❤️❤️A post shared by Demi Lovato (@ddlovato) on Nov 13, 2014 at 12:47pm PST... Looking good Demi!VIDEO: Kristen Bell Loves 'Frozen' Even More Than Your Kids DoET was actually with Frozen stars Kristen Bell, Josh Gad and Idina Menzel last October, before the animated film became such a massive hit.Check out the video below to hear how the movie made Kristen's dream come true.