Talk streaming is exactly what it sounds like: you talk out loud, non-stop, for a long stretch, about your problem and anything else that comes up. You don't plan, you don't polish and you don't stop to judge. When the words dry up, you carry on regardless, even if what comes out is nonsense.
Speech is fast and hard to edit, so it slips past the inner voice that shoots ideas down before they're finished. As you use up the obvious thoughts, the worries and the old arguments, space opens up for something new. Often the useful idea surfaces after you've drifted far from the topic, and you only notice it because you heard yourself say it.
You need an audience of some kind: a friend willing to just listen for half an hour, or simply your phone's voice recorder on a long walk.
Use it when you keep circling the same few thoughts, writing feels too slow or too formal, you think best out loud, or you need to clear your head before you can see the problem clearly.