The advantage of a podcast made available by way of iTunes is that it opens such programming to a wide audience of potential listeners immediately. The other options - live streaming online audio and downloadable MP3 files on the blog's Web site - can also be undertaken without impairment.
As for video, I would suggest that instead of "talking heads" that any video aspect of these presentations be prepared in PowerPoint format and be made available online as password-protected PDF elements? There's a great deal of information to be made available in graphic form which the mainstream media do NOT provide. As a visual supplement to verbal offerings, there's much "value-add" in such materials.