You can't do the same kinds of task together, but you can sometimes do 'multi'-tasking as long as it is an entirely different part of your brain...
For example, you can do a task that takes mental concentration, while doing a physical task that you can do on auto-pilot.
E.g. Listening to a complex podcast, while jogging. Watching a TED Talk while washing the dishes (I love laptops).
What you can't do, is the same kind of task, or two complex tasks at once. Thinking about a programming task, while trying to pay attention to a webcast. Same-same, see?
You need to adjust the tasks you are multi-tasking, to make sure that you have enough concentration for both. If there's any chance you'll get so engrossed in a podcast that you run off the road, that's too complex. Stick to music instead.
This can be useful, for when you are doing a task that doesn't engage all of your attention. I.e., is boring.
Check out this article:
You may be doing a boring repetitive task, say adding up spreadsheets, and in cases like this, a little bit of distraction, eg music or a really light podcast (more entertainment), can keep you on task without getting distracted.
If you find yourself distracted, or unable to concentrate on one task, then one of the tasks is too complex.
I have a little continuum, like:
Familiar Music without words - Unfamiliar music with words - Light entertaining podcasts (that you can 'get the gist of' without learning too hard) - Complex learning podcast
Depending on what I'm doing, or how much energy I have, determines which I can listen too.