I haven't seen this before. I really like it!
Our low water hand washing is done with a garden hose. I attached one end to a three gallon
bucket, which is kept about seven feet off the floor. The other end hangs over the the edge of our sink (a big steel mixing bowl) and has a ball valve. You only need the tiniest trickle to wash hands because of the elevated bucket providing some water pressure. I usually use less than a cup of water.
You've got to turn the valve off and on, so it's not hands free, though :(
Looking at other tippy tap examples
online, it seems like playing around with the length of the rope and placement of the stick will keep water from pouring directly on your feet. If it's just splashing, maybe putting the recommended gravel underneath would help.
I'm glad I saw this. Will set one up for our outside washing next summer.