Lars IS a teacher – that's what he is employed to do by Autodesk. Although he has his own channel, he is an Autodesk employee and sometimes appears on the Autodesk / Fusion channel.
John Saunders is also a good guy to watch – he often shows how to do the CAD, then the CAM, then machines the part on his Tormach or Haas machines.
No, there's no catch. No limitations and you get the full "Ultimate" version which will soon include 5 axis simultaneous CAM. As long as you can declare that you are a hobby user or your business turns over less than $100k pa, it remains free and I was assured by one of their product managers that this will not change. It's just a refreshing challenge to the cosy, almost contemptuous dominance of the likes of Solidworks (and Solid Edge) who have been demanding eye watering "support" payments on top of eye watering purchase costs. That's the opportunity that Onshape and Fusion have grasped. The difference between them is that Autodesk (Fusion) already owns quite a few add-ons such as FEA and CAM (they own HSM Works) and they have Inventor / Autocad features etc to draw on. Integrating all that stuff into one combined ("fused"?) offering is pretty exciting and must seem like an unfair advantage to the likes of Onshape who have started from scratch and can only offer paid-for 3rd party add-ons.
Murray