Revealing the atomic dance in glasses has been always considered an extremely challenging experimental task due to the weak scattering signal of glasses and the long time scales involved in their dynamics. In a recent beamtime, we successfully took advantage of the large coherent fraction of the x-ray beam produced at ESRF-EBS to measure for the first time the intermediate scattering function of a metallic glass on spatial length scales covering both inter-cluster and intra-clusters distances. Our data suggest the existence of a continuous transition between distinct mechanisms of collective motion on approaching the macroscopic limit. We propose to confirm these results by extending the dynamical range at length scales far from any structural contribution. The results will help clarifying the origin of an anomalous compressed decay of the ISFs in metallic glasses at the atomic level, which is puzzling the community since more than ten years.