Afaict, it was never finished?
As far as I understand, it never got released unfortunately. Would still be a great resource to have!
The manual is more technical and less practical for beginners. And the haxe conference videos are plenty and good but the video quality is low, and most of the older videos do not display screenrecord of slides instead the recorded the presentation with the video camera itself, so the slides/code cannot be read with that video quality.
So, I completely agree that a mooc/updated book/(properly recorded) video series about the language itself (not some game framework) would be very good.
There is also code.haxe.org which has many real Haxe code examples, which are not framework specific. This might help you!