Normally people don't follow links to external websites but I did and to ruin your excitement:
This has nothing to do with bonsai. It's just a very young boxwood in a far too small pot.
And again, I'm repeating myself: this is NOT the way to grow bonsai. This plant does not belong in a bonsai pot. Keeping small plants in small pots will only stunt the plant's growth, keep it small and undeveloped, and eventually kill it.
Please do a bit of reading, this is really repeated on an almost daily basis.