Justin Timberlake had Britney Spears in the mood to shake it last week. Spears took to Instagram on Wednesday to share a sultry dancing video of herself moving to JAY-Z's 2013 song, «Holy Grail,» which features vocals from Timberlake. Spears, who split from Timberlake in 2002 after three years together, wore a black cropped turtleneck and plaid shorts in the video.