Shalom veritas_libertas! What got me through the eCPPT course on that topic wasn't the PTP material alone. I actually found the material from Pentester Academy to be incredibly helpful. In particular Vivek's Exploiting Simple Buffer Overflows on Win32 (located below):Exploiting Simple Buffer Overflows on Win32
I obtained the eCPPT Gold back in September/October of 2013. Cybrary wasn't around at the time, but another helpful resource for you that won't cost you anything will be the Buffer Overflow Sections inside of Georgia Wiedman's Advanced Penetration Testing training course located here.
Highly advise feeling very comfortable about the subject of Buffer Overflows before you take the exam