Develop a plan for video training by narrated PowerPoints

I need someone with expertise in presenting online educational videos to develop a plan for me to create an ongoing series. Criteria are as follows: 1. I need users to be able to record 40-60 minute online training sessions on their own computers that don't have extra-cost software installed, just PowerPoint. These presentations will be narrated by those users. I need suggestions on whether to use PowerPoint 2010's narration function, a separately recorded audio file to be merged with the PowerPoint after the fact, or an online service that allows someone to narrate the slides over the telephone. The recording process needs to be simple with no involvement on my end, just the user doing whatever the instructions suggest and then sending me the file(s). The end result will just be a narrated PowerPoint that can be streamed from any PC. I do not need functions related to quizzing or user input -- users will just view the presentation like any other video 2. I need a recommendation on how to convert those audio/video files to a format that can be streamed as a video with sound. I will do that on my end, using standard video tools like Camtasia if needed. Or, I'm willing to use an online service if my other requirements can be met. Should I use flash, MPEG, etc.? 3. I need suggestions on how and where to host those files so they can be streamed. Do I need a separate video host (I have a virtual private server), a separate hosting account, or an online service? 4. I need a method to require viewers to sign up on an online form before being allowed to view each video on the recommend hosting service. The videos should not be publicly visible -- I want to develop a page that lists the titles that can be clicked, but I don't want the videos to show up publicly and viewable without signing up first (the signup will be used for sales leads). I've looked at various online PowerPoint conversion services as well as video streaming services such as Vimeo Pro that only stream the final result. Tell me which I should use and why. If I wanted to put together a curriculum of 50-100 courses, how should I do that? I'm looking for help with a plan on how to do this -- not someone to do the actual work at this point. I'm interested to know your credentials and background and how you can help since I need someone who knows more than I do. I like the idea of recording Webinars, but I don't really need the real-time presentation with online users -- I just need to record the training session and stream it on demand. If you have knowledge and experience that allows you to tell me the best way to do that, then I would like to hear from you.