https://www.nintendo.com/switch/system-update/
Nintendo said:- Video capture for select games
- New profile icons featuring characters from the Super Mario Odyssey™ game and The Legend of Zelda™: Breath of the Wild game
- Transfer user profiles and save data to another system
- Pre-purchase option is available for certain games on Nintendo eShop for Nintendo Switch"
"To capture video, hold down the Capture Button during gameplay
Up to maximum of the previous 30 seconds will be saved in the Album. You can trim the beginning and end of each clip, and post to Facebook and Twitter.
As of October 18th, 2017, this feature is compatible with The Legend of Zelda: Breath of the Wild, Mario Kart 8 Deluxe, ARMS, and Splatoon 2"
More details here. So yeah, only 4 games support video capture, but it's a start.