This way of strumming the banjo is a precursor to “frailing” or “clawhammer” style of banjo playing, which is the style we recommend for beginners.
If you're planning on learning to play three-finger banjo (i.e., bluegrass-style banjo, played with fingerpicks), we still recommend that you start with this basic strum for Shady Grove. Save the intricacies of three-finger banjo for later.