The future of metallic glasses as an advanced structural and functional material will to a great extent depend on the understanding and control of their mesoscopic flow defects called shear bands. These defects are sweet-and-sour; sweet because they mediate macroscopic plasticity at room temperature, and sour because they quickly promote failure. In the past decade, fundamental research generated great progress in characterizing the role that shear bands play during plastic deformation of disordered systems, including metallic glasses. Similar to those in many other materials, shear bands in metallic glasses are only active for a very short time, which directed research focus towards topological, structural, chemical, and thermal properties of formed, but inactive shear bands. In this paper, recent progress in directly characterizing the shear-band dynamics in situ during straining experiments is presented. Various shear-banding stages are outlined, including formation, propagation, and arrest, as well as shear-band creep and aging. The results are discussed in a more general context of disordered materials, concluding with a summarizing overview of time-scales involved in shear banding, and describing future research directions that may lead to controlled shear-band plasticity in metallic glasses.