Stumbled upon this online. Didn't know it existed, in 1977, I think. Also, I came across a transcript of it which I downloaded in PDF.
In the end, the question Sproul had was "How do you know the Christian Bible is the Word of God. Why not the Quran?" I remember Sye Ten Bruggencate famously refuted the Quran by saying that it supported the Bible and thus contradicted itself.
Since Kant refuted all previously known arguments, Stephen Tong borrowing from Kant saying that there can be no good arguments for God's existence. Thus, we are left with the transcendental argument. Which is probably what Van Til picked up for his presuppositional apologetics.
Common error of this is that many mistakenly thought that this apologetics refuted the others (classical, teleological, etc.) But in fact, it infused within all of these, hence the confusion in the debate. Bahnsen's soundbite response to that is just "by the impossibility of the contrary", again and again.