We don't expect individual professors to write their own textbooks for every class they teach. That would obviously be an absurd waste of time - it's far easier to use a textbook already written by someone else.
So why do we expect every professor to plan and present their own lectures? Imagine the quality improvements that would occur if we followed the same distribution model for lectures as we do with textbooks: The best, most well-spoken professors in the world, presenting well-rehearsed and polished explanations of their material in Blu-Ray, delivered or streamed to lecture halls and student's laptops all over the world.
You might object that this robs the student of the ability to ask questions if they don't understand something. But do they really have this ability now? In my experience, students are already hesitant to ask questions when they don't understand something. With a pre-recorded lecture, students could pause, rewind, consult their textbook, ask a friend or look something up on google. On the rare occasion that this kind of self-directed learning fails, a student can make use of optional tutorials or their TA's office hours.
I think we would see an immediate and substantive increase in teaching quality if we adopted this model. More importantly though, outsourcing lectures creates an industry that rewards continuous improvement and encourages innovation. If you think we'll be impressed by the first generation of lectures-on-tape, imagine what we'll be seeing after a decade of testing, focus groups and quantitative analysis of different teaching methods and exam performance. Aside from the inglorious transition from chalk to overhead projector, there hasn't been any sort of innovation in teaching and education in the lives of those now living. Outsourcing lectures will create a strong incentive to improve and refine teaching techniques.
Finally, consider the egalitarian implications in a world where an entire undergraduate degree can be obtained from textbooks and videos. Education would no longer be the sole prerogative of the wealthy and privileged. Anyone with access to an internet connection could receive an education of higher quality than is available to 99.9% of the world today. Universities would continue to exist, focusing on their core competency as research institutions. World peace would reign, the blind would see, and there would be a rainbow every day.
The technology exists. The initial implementation would be tricky, but once this takes off, it really takes off. Economies of scale and all that. I'm a little too preoccupied to start Lectures 'R Us right now, but if any of my loyal readers aren't, please feel free to go ahead and make a billion dollars.