It's easy to calculate how many beads you will need, If you work with a bead every other stitch, divide the number of stitches you are binding off by two, and string on that many beads. If every third stitch, then divide the total number of stitches by 3! You'll want to swatch and see if you like the bind off with size 6 or 8 beads, that depends on the size yarn you are working with!
Disclaimer: this video was made at my kitchen table, with minimal equipment and lighting... Enjoy!!!!