But performance across the two games showcased in the new video by YouTuber Mizumi, Super Smash Bros. Melee and Paper Mario hovers in the 20-25 frames-per-second range. Emulation on the Switch is made possible via the Linux-based OS Lakka, and isn't running on official firmware. So, in reality it's not a Switch we see but a home-brew machine in Switch clothing.
Interestingly in the later part of the video we get confirmation that the Switch is running Lakka emulators for Virtual Boy, PlayStation, PSP, and other consoles too. This is all possible due to a recent Nintendo Switch hack that was discovered at the hardware level via Nvidia's Tegra X1 processor USB recovery mode.
When that news came to light a couple of months ago, it sparked a home-brew Nintendo Switch scene to emerge where console's were then purchased for the sole purpose of hacking, switching to a Linux OS, and seeing what was and wasn't possible on the hardware.