There was no mention about executing anything in the heap (or stack for that matter). I have no reason to believe VLC maps (a part of) its heap RWX (=read + write + execute). This kind of exploits don't even require memory to be executable.
C++ virtual methods cause the compiler to add vPtr (that is writable, because it's contained in the object) and vTable. Modifying vPtr can be used for making certain class execute code somewhere else (or mostly crashing :-)).
However, neither vPtr and vTable themselves are executable. vTable doesn't even need to be writeable.
If you can somehow do indirect vTable reads, you'll learn ASLR [0] base for the module. With that information you might be able to circumvent ASLR, and eventually be able to pull off code execution through a ROP [1] chain.
A C-style function pointer would be easier to use for a similar effect.
[0]: https://en.wikipedia.org/wiki/Address_space_layout_randomiza...
[1]: https://en.wikipedia.org/wiki/Return-oriented_programming