We're trying our best right now to find potentially interesting instructors. There are 2 or 3 people who might be adding content in the near future. YouTube and TeacherTube (and other sites) already exist for anyone to post a lecture. We think our value is in providing a handful of lecturers that really resonate with students. If I had to guess, we'll have 10-20 lecturers in English within the next 5 years.
Try to be careful with this.
I think one of the reasons why Khan Academy is so great is because people know you are creating the videos. We know what to expect before watching a video. I think there is also a sense of a personal connection, people feel comfortable with you.
Of course I hope for the best, and expanding seems reasonable at this time.