The Nikon D3400 supports a maximum video resolution of 1920 x 1080 pixels. That's over two times the video resolution of a 1280 x 720 pixels camera, which is the most frequently found video resolution supported by comparable spec cameras that have been available for the last year. 1280 x 720 pixels is also supported by this Nikon camera. A video resolution of 1920 x 1080 pixels is equivalent to Full HD video. You will require a Full HD TV or better to appreciate this level of detail.
This digital camera's video resolution (1920 x 1080 pixels) is in fact the best supported video resolution across all newly released comparable spec digital cameras.
Across similar types of digital camera the worst supported video resolution is 640 x 424 pixels.