I will not be showing the Groom Card Generator in this stream unfortunately, but have a long breakdown planned which will show it in full detail. 
The actual process of creating the HDA from a Heightfield will not be covered in this stream, but I will be showing a Heightfield HDA in action within Unreal!
If you have any additional questions / would like to get more detail on what we are showing after the stream let us know!
Cheers,
Paul