Short answer, you can't.
When PTC/USER ran the conference, all presentations were made freely available to the broader community a couple moths after the conference was over. Since PTC has taken over running the conference, PTC has stopped allowing public access and now only provides the the presentations to those who actually attended (or at least paid to attend) the conference.
PTC/USER is now running their own separate winter event each year and those presentations are still available to anyone who registers on their site. (Registration is free.)
