It all depends on your goals. But your the creator, you can make that decision yourself.
I can say that we have a number of podcasters that are using video cameras to record their audio production and post that video along with the audio. The audio garnishes more downloads typically, but the video attracts a different audience. From our Blubrry Statistics
and our Programs featured Blubrry TV Apps
we've noticed that video is more likely to be consumed on TV apps such as Samsung SmartTVs, Google TV, Apple TV, Roku and Boxee.
As Todd Cochrane says, if you want to be on "all glass" (aka TV, phones, tablets, computers, etc..) then producing a video version of your audio does just that.
With that said, I personally don't like producing video, it takes way more work and it's much harder to achieve the quality necessary for today's TVs.