Time-resolution is one of the main limitations for scanning probe microscopy (SPM) investigations of surface processes under in-operando conditions. To overcome this constraint, we developed an add-on fast-scan module that can drive commercial SPM at and beyond video rate image frequencies, allowing to investigate dynamical processes at surfaces with millisecond resolution. Our FAST module requires no modification of the existing scanner hardware and electronics, and its operation is totally transparent, allowing the user to switch immediately and seamlessly to the fast scanning mode when imaging in the conventional slow mode. The unit provides a completely non-invasive, fast scanning upgrade to common SPM instruments that are not specifically designed for high speed scanning. To test its performance, we thoroughly used this module to drive commercial scanning tunnelling microscope (STM) systems (Omicron VT-STM and LT-STM, SPECS Aarhus) in a quasi-constant height mode up to frame rates of 100 Hz and above, in a temperature range between 77 K and 600 K, demonstrating extremely stable and high resolution imaging. Moreover, the flexibility in controlling the module opens up to new capabilities, as demonstrated by the atom tracking feature we already developed. In principle its application is not limited to STM; to this aim, we are presently working to extend its use to atomic force microscopes (in collaboration with Jordi Fraxedas and Daniel Tiemann at ICN2). This project has received funding from the EU-H2020 research and innovation programme under grant agreement No 654360 NFFA-Europe.