Part of a bizarre art installation. I caught 2-3 minutes of it, was too fatigued to watch more. A series of Headstone shaped video screens, playing different videos synced to a soundtrack. This was a series of skeletons dancing. (May have been the same video on all with a delay between them.
Here is a video of the installation, I obviously only saw a small part of the video
Located in the Totentanz, a small wedge shaped park west of the 3 Kings Hotel (Grand Hotel Les Trois Rois). Totentanz is the Dance of Death, named for a famous painting that used to surround the cemetary at this site.
Wiki entry on Totentanz, use Chrome to translate to English