Hi @Hibatchi Welcome to ZBrush Central!
If you select a different shape from the set every time you draw one out, then each one will have a different polygroup. If you are drawing the same shape multiple times then there is no way to do this automatically that I am aware of. It’s easy enough to group it though. When you draw out your insert, it masks the underlying mesh that you are drawing on. Holding down Ctrl, you would click on a blank part of the canvas to reverse the mask. Now, the insert would be masked at which point you would press Ctrl+W for “Group Masked Clear Mask” or click the button in “Tool > Polygroups” subpalette. Each insert would have a different polygroup.
Other than that… can you provide a link to the video at the exact time this starts to happen?