This thread also shows a good way to do it that does not require a 3rd party app, and does not require the delay, etc:

https://www.reddit.com/r/tasker/comments/2x2ky9/set_variable_if_media_playing/cowdq1f/

However, it would still be nice if the player would just broadcast an intent when it starts or stops playing. BeyondPod did something like this, which included the name of the podcast feed, and episode, etc.. and I used it to make a small text-file log that I could consult later. E.g., "What was the name of that one podcast I was listening to last weekend that was talking about squid?" or "I fell asleep listening to X last night, and woke up listening to Y, which episodes did I miss while sleeping, so I can undelete them?" etc.. The later use case is covered by the recycle-bin feature in PA, but it is still a useful thing to broadcast intents like this, and users can make use of them in a variety of interesting ways.

Try using "Tasker Is Music Playing" plugin. Pay attention to the directions: You need a profile, a task, and a 2-second delay. But it works! I used it to see if I need to pause/restart podcasts when Tasker voices my text messages.