That is sort of strange... and I could see how that login might put people off from using the service.
Conventional thinking regarding most information on the internet is "if you provide something (a service, etc) to the user, you have the right to request some minimum information from him/her". Many internet sites and services seem to adhere to this reasoning. So although the videos are free, PTC is using the opportunity to collect usage information in the form of a login.
I had begun assembling a web service to offer completely free videos and tutorials. But it's tough to compete with the sheer volume of tutorials put out by PTC. It seemed like it wasn't such a great use of my time to try to out-do them... so I rather abandoned the idea. There's a rumor that some of the latest videos I created for Ninja Cabling are supposed to be added to the free Learning Exchange. We'll see if they make it... I'm not sure if PTC will be willing to put a customer-created set of videos onto what is essentially a corporate controlled site but we'll see.