R. C. Sproul nails it. (Click on "the age of the universe" link on this page.)
Al Mohler blows it. He begins with an argumentum ad populum: well, lots of church fathers believed in a young earth! This is an especially specious argument because he never points out that they had no reason to believe otherwise. Had they held fast to a belief in a young earth in the face of overwhelming data to the contrary he'd have a point. Also, he is selective in what he draws from the church fathers, never pointing out that while they thought the who and the what of creation was important enough for the historic creeds, they didn't seem to care to much about the when. Nor did honesty incline him to point out that the early church consensus on a young earth extended to an early church consensus on a geocentric universe.
His arguments never improve.
He repeats, unabashedly, just about every dumb argument ever made. He criticizes "uniformitarianism" or the idea that the laws of physics have not changed. He never addresses the counter-argument: OK, let us, for the sake of argument, toss out uniformitariansim (even though there is zero evidence for doing so.) You are still left with a big problem. That might explain why the radiometric data are wrong. That might explain why the astronomical and astrophysical data are wrong. That might explain why the geological data are wrong. But it doesn't explain why the different radio isotopes give the same wrong answer, and it doesn't explain why the aforementioned astronomical, astrophysical, and geological data all give the same wrong answer.
One of the more obtuse arguments Mohler makes is that it is more or less unimaginable that (as OECs would claim--at least those who wish to preserve the historicity of Adam) God would intervene to specially create or ensoul Adam and Eve. This is bizarre--why would Mohler find it unimaginable for a God who created the universe to intervene, in what appears arbitrarily to us, at any time in history that it pleases Him?
Sproul gave an honest (and correct) answer. Mohler gave a dishonest reply, never mentioning the considerable flaws in his own arguments.
I feel a little dumber after listening to his talk.