Billy Berger's video series on the spearthrower is now complete. I reckon it is hands-down one of the best presentations of this subject. He doesnt say a whole lot about the flexibility of the spear which is the most important part of the system, but the slo-mo sections in the last video show he has got it right.
https://www.youtube.com/watch?v=QQQ8u5eqwXc
https://www.youtube.com/watch?v=cgkyxY6lmRo
https://www.youtube.com/watch?v=wfOMQqM8ytM
https://www.youtube.com/watch?v=BsW7ERQHHJQ
https://www.youtube.com/watch?v=iaFfOhouSls
The other go-to guy on YouTube, who got me into making atlatls and darts several years ago, is Tom Mills:
https://www.youtube.com/watch?v=nTatpBIdTmQ
https://www.youtube.com/watch?v=n_zkAdHrU_A
https://www.youtube.com/watch?v=68FnPc76BMs
https://www.youtube.com/watch?v=uhrJ6kaojwM
https://www.youtube.com/watch?v=j8vctRvjLcY
https://www.youtube.com/watch?v=QQQ8u5eqwXc
https://www.youtube.com/watch?v=cgkyxY6lmRo
https://www.youtube.com/watch?v=wfOMQqM8ytM
https://www.youtube.com/watch?v=BsW7ERQHHJQ
https://www.youtube.com/watch?v=iaFfOhouSls
The other go-to guy on YouTube, who got me into making atlatls and darts several years ago, is Tom Mills:
https://www.youtube.com/watch?v=nTatpBIdTmQ
https://www.youtube.com/watch?v=n_zkAdHrU_A
https://www.youtube.com/watch?v=68FnPc76BMs
https://www.youtube.com/watch?v=uhrJ6kaojwM
https://www.youtube.com/watch?v=j8vctRvjLcY