Yes, it's real. I don't have a video and I don't have a metal workshop any more but you can easily try this yourself if you feel like it. For added speed you could add some sand, and if you're just interested in the effect mix some rocks with some wooden blocks, that will speed things up quite a bit.
It's similar to how river beds tend to round the stones that get moved around by the water. Those stones start out as sharp bits of rock.
It's similar to how river beds tend to round the stones that get moved around by the water. Those stones start out as sharp bits of rock.