Tested on: Lenovo Legion Laptop
Dual Setup: Laptop records footage from the Nintendo Switch OLED while external monitor displays the game.
Instructions: Plug the capture card into your laptop's USB port. Connect the HDMI cable from the Nintendo Switch to the HDMI Input port and the HDMI cable from the 2nd monitor into the HDMI Output port.
For a single-monitor setup, simply plug in the HDMI cable from the Nintendo Switch to the HDMI Input port and in OBS, switch to full screen.
When plugging in the device, there's no sound feedback so be aware of that. In order to check that your capture card is properly installed, we are going to use the Device Manager.
Under Cameras, you should see USB Video. If it doesn't show this device, try plugging the capture card into other other USB ports.
Next, we need to verify security options.
Go into Windows Settings > Privacy > Camera
Make sure Allow apps to access camera is checked and make sure OBS has permissions to use your camera.
Close OBS and launch it once again if you haven't.
In Sources, add a new source: Video Capture
Device: USB Video
You should see your Nintendo Switch home screen (make sure the console is not on standby)
No Audio Fix VMKLY 4K HDMI Game Capture Card
After a few recording tests, you might notice there's no audio from the game.
Double click on the Video Capture source you just added and scroll down to Audio Output Mode and make sure it says Capture Audio Only.
Check Use Custom Audio Device and select Digital Audio Interface (USB Digital Audio)
Your video capture device should now be lit up in Audio Mixer.
That's all. Enjoy recording gameplay.