Where it pays off is not when you reach parity with the built product compared to the vendored product - it's when you can continue to extend or customize the capabilities when the original vendor can not or will not support the features you can now build
How does this perform on longer videos, especially on lower-end machines? Is the transcription and video processing entirely local in the browser?
Whilst I love opensource; hitting with $24/mo saving when you invest 100x that much in your time is probably not the way to sell it.
Where it pays off is not when you reach parity with the built product compared to the vendored product - it's when you can continue to extend or customize the capabilities when the original vendor can not or will not support the features you can now build
I promise you something like this will never monetarily "pay off."
From the commits, it looks like it only took OP about 4 hours with Cursor.
The name has a collision with a programming language related to ocaml - ReScript, which evolved from ReasonML