It works fine.

The reason why you don't see much of this usage is because, the way it's designed, it looks like a really "private" method.

Plus it throws instead of returning an HRESULT. Personally, I always prefer returning an HRESULT instead of throwing (even if you carry a ComPtr around), because it's easier to handle.

Here is a (more convoluted, I admit) way of doing it that looks more "COM" (or more "Microsoft" if you will):

HRESULT GetSample(REFIID riid, void**ppv) // you can add other parameters (in front, and leave riid and ppv last)
{
  HRESULT hr = S_OK;
  CComPtr<IMFSample> pSample;

  hr = MFCreateSample(&pSample);
  if (hr != S_OK) return hr; // or if (FAILED(hr) ? depends if you handle S_FALSE an other non error cases

  // ...Create buffer, Add buffer, etc...

  return pSample->QueryInterface(riid, ppv);
}