The highest video resolution supported by the D5100 + AF-S DX NIKKOR 18-105mm f/3.5-5.6G ED VR is 1920 x 1080 pixels. That's over six times the video resolution of a 640 x 480 pixels camera, which is the most frequently found video resolution supported by cameras of this type and age. In addition, this camera support a video resolutions of 640 x 424 pixels and 1280 x 720 pixels. 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 camera's video resolution (1920 x 1080 pixels) is actually the best supported video resolution across all digital cameras that were released more than two years ago.
Across comparable types of camera the worst supported video resolution is 320 x 120 pixels.