This is more complicated. I knew about "Tu stai parlando." The question is whether "Tu parli" can also be translated as "You are speaking." Here's a place that translates the Italian present tense with the English progressive present: http://quizlet.com/19220958/presente-dei-verbi-in-are-present-tense-of-are-verbs-flash-cards/ But I rely mostly on this: "The difference between, say, Legge il giornale and Sta leggendo il giornale is not necessarily that between English "She reads the newspaper" and "She's reading the newspaper." In modern colloquial English, if the event described is simultaneous with the time of speaking, there is no simple alternative to saying "She's reading the newspaper"; but Italian allows either Legge il giornale or Sta leggendo il giornale, using the latter only to underline the progressive, developing nature of the activity. Similarly, in the past, "She was reading" corresponds both to Leggeva il giornale and to Stava Leggendo il giornale." from (Maiden and Robustelli, A Reference Grammar of Modern Italian, p. 303). Of course, I'm not a native speaker, and I defer to those who are.

Agreed. Italian has a progressive form, too, and it wasn't used here. So it is safe to assume that the simple present should be used.