Lectures are traditionally one-way broadcasting of material. Rather than just making videotapes, it's much more effective to think through the available technologies, and pick those appropriate for your material. The remaining part, the two-way discussion, can be done electronically. If you normally use slides in class, you can narrate a presentation or include major points in the notes section.
Presentations can include graphics, pictures, hyperlinks to pertinent sites.
Not very difficult to create. With current versions of software available, one cannot use the animations feature of powerpoint on the web. Complex slides can take a long time to download. Add color, graphics, hyperlinks to increase interest and interactivity of pages. Video and audio can be much more engaging than text.