You can now record video on Nintendo Switch

[TomaTito]

Just some additional info on the video capture format (which is the same for docked and handheld):
It's an MP4 file, 1280x720 resolution, 30 fps, encoded as H.264, with AAC stereo audio at 48kHz. The bitrate is 4.38Mbit/s.

https://www.reddit.com/r/NintendoSwitch/comments/77b1vn/video_capture_details/