This exhibition presents an investigation into the folk music and dance practice polska, involving a group of Swedish folk musicians and dancers. The investigation employs optical motion capture (mocap) to explore interactive music and dance performances and create innovative artistic expressions by merging traditional practices with contemporary media technology. As a musician working closely with the dancers he plays for, the author explores ways to mediate dance through the sonification and visualisation of movement data. The focus is on the fundamental connection between sound and movement in this performance practice, particularly showcased in the project's centrepiece, Dancing Dots. Documentations of this and other works included in the exhibition present live music and dance with sonic and visual displays derived from mocap data, asking how such multi-modal mediations can facilitate understanding of the interplay between movement and music and open new avenues for artistic expression in this folk music practice. The use of optical motion capture is contextualised as a means of mediating music-dance through narrow streams of movement data, and the exposition introduces a web tool for accessible sonification of folk dance. The exposition applies music and dance theoretical concepts in designing the movement mediations, examines their relevance in an artistic context, and grounds the results in a practice-based understanding of the rhythmic/metric framework of the Swedish polska.