recording software interaction + video of user

Please forgive the newbie question. In all honesty, I'm not so much a newbie as a never-be, when it comes to this issue.

My client, an online educator, wants to create a webpage showing a student and teacher working on a lesson -- the student at her home, the teacher in her office. My first thought was Camtasia, to record an actual screen session. I'd want to add a small window cutting back and forth between the student and teacher, in sync, as they talk through the lesson.

I was concerned about the download time for someone to look at such a page. But it seems that a lot of people use Camtasia to create Flash movies, which for some reason don't have the bandwidth demands of regular videos. This mystifies me (I told you I was ignorant.)

Would a Camtasia->Flash movie work, or should I look for a programmer who can actually recreate the training session in some more sophisticated and compact format? Could I create a Camtasia/Flash movie of an online learning session, and then add synchronized videos of the teacher and student later, or would that destroy the whole idea? Could I record both ends of the conversation, one at the student's home and one at the teacher's office, and then intercut between them?

Thanks for your patience.

-- bob c