I would recommend an Android device that supports USB on-the-go (OTG). USB OTG is not commonly available nor much talked about, but I have found it very useful. I am using an 8 inch Samsung Galaxy Tab 3 with USB OTG support. I usually leave the tablet in my car.
Basically, OTG allows your Android device to act like a host computer. Normally, if you plug an SD card into a computer, the computer will recognize the card and allow you to copy to/from the card and play media files on the card. However, it you find some way to plug an SD card into the
external USB port of an Android device, the device will not recognize the card. You will have to plug the card into the
internal card slot on the Android device. The internal slot may already be occupied, however, and replacing it might cause problems with the functioning of your device
USB OTG solves the problem and allows Android device to act like a host computer to access the external, temporary SD card, for copy to/from and to play media files.
Here's why what that is good.
Although the BlackVue WiFi is convenient for changing dashcam settings, it is not good for looking at video. The video is slow to load from the BlackVue to an Android device, and the video is constantly interrupted by buffering. If you have an accident and want to show video while at the scene of the accident, you have to be within the short WiFi range, the car has to have 12 volt power, and other people have to be patient while you try to find the correct file to play, and they have to be patient with delays caused by the constant WiFi buffering. All this may be difficult with a wrecked car.
With my Android device, I just remove the SD card from the BlackVue, plug the card into the external USB port on the Android device, and play any file with no interruption.
This shows the BlackVue SD card plugged into the BlackVue supplied adapter (red part) which in turn is plugged into a USB cable that connects to the USB port on my Galaxy Tab. The "My Files" Android app is opened, showing that the dashcam video files are located at /storage/UsbDriveA/BlackVue/Record. This is useful to do one time to make sure you know where the files are.
Here is a clearer screen-shot.
I start the BlackVue app on my Galaxy Tab and on the home screen, select "Search microSD".
Then I select "/storage/UsbDriveA" and press the "select" button.
Then, back again at the home screen, select "BlackVueSD". This screen then appears, showing all the videos available to play.
You, of course, see the same video list if you connect using WiFi, but now each video plays immediately and with no buffering interruptions. This can be useful if you are dealing with a cranky police officer. (Of course, if you are at fault, do not do any of the above!)
A video playback: If you have an Internet connection, the mapping window also works.