I remember looking up if video playback was a Nintendo Switch feature before deciding to purchase it so that I could ditch the smartphone and have some anime on my 128 GB microSD card, but what I found was that no, playing video files from the Switch is itself is something you can only do with a modded Switch for now. There are alternatives, however, like using Plex and the Switch's "hidden web browser", or YouTube and whatnot, but that's not what you're looking for.