Yes, but most, if not all, of the concept has been done before. Given that, I think the question why things would work better this time is one that the backers of this project should think about before starting development.
My input would be that I think the cute displays in the video will not work on real-scale projects. One reason is that I do not see how the most interesting part, the live display of a call graph, will work as nicely as displayed in the video with:
- functions that manipulate disk or network state
- large functions
- deeply nested functions, in particular recursive ones
I can envision each of them, but all in a somewhat ugly way. The first would require programmers to write set-up and tear-down code; the second and third would eat screen real estate and/or would involve scrolling and/or collapsing.
If you have to write that setup and teardown code, I do not see how this interactive way of testing code is that much better than writing unit tests.
Translating that into constructive feedback: I would aim for building a good tool for education first; then, work on the scaling problem. But, be prepared: you should be happy if you get the education part only; you may not find a way to scale this up to real-world projects. And you should also realize beforehand that, if this does not scale, the educational program may be seen as a toy, only useful in the first half-year or so, only because 'real programmers' do not use it. It may take time to overcome that, just like it took (or even: is taking) time to overcome the notion that real programmers do not use IDEs.
[Going on a tangent: I would love to have a system that allowed me to split unit tests into API examples and all the other tests (timing tests, integration tests specific to certain bugs, etc.) That way, the documentation system could grab the first kind of tests and show them in the documentation.
I also would like to see a system that forbid me to write code that is not covered by a unit test yet. For example, in C, it would force programmers to write the header file first, the unit tests exercising part of the code second, and the actual code last. It should allow me to write the whole header file, then implement and test that header in parts, though. I also might hate it the moment I see it, but I need to see it to discover that.]