I was just starting to put together the HDMI capture board. The stand-off screws will fit the HDMI board itself, but are too big to pass through the mounting holes on Raspberry Pi 3. You may wish to check before further shipments.
Mike, thank you for the feedback. I’m sorry that you had a problem with this, but there are some variation between the Raspberry Pi boards. My partner pointed out to me that our documentation includes a statement “Note that the size of the mounting holes may vary slightly, and it may be necessary to gently ream out the holes slightly for the screws to fit.”