This is something really cheap, that can provide you some useful information about your quad and adds quite some excitement to the videos. Below video was created with the ‘Cleanflight Blackbox Explorer’ which is an application that is part of the project and runs within chrome.
On the hardware side you only need to spend about $10. The device used for logging is called ‘OpenLog’ and it logs the telemetry data on a Micro SD card. These tiny devices are available from eBay for cheap. Some sellers claim, that the devices they ship are for Blackbox. The difference would be a Blackbox logging optimized Firmware instead of the stock OpenLog FW. But the device I received still had the standard OpenLog firmware flashed. It might give you some more consistent logging and you can reflash it. But all my attempts failed so I gave in and use the OpenLog FW instead. I have not discovered any disadvantages yet.
The OpenLog device is hooked on one serial port on the Naze. I used UART2 for that purpose and all you need to connect is the RX wire to TX. To power it, you connect 5V and ground to one of the ESC plugs or wherever you like. Don’t forget to configure the flight controller accordingly. Blackbox needs to be enabled in the Cleanflight settings and Telemetry assigned to the corresponding serial port you use. The port I used (UART 2) is on the left site, looking on the Acro Naze 32 with ESC connectors facing away from you.