Here's the app title: VRPlayer : 2D 3D 360° Video
Here's the link to the app store: https://rb.gy/z164l
Here's the app icon
Here's a QR to the app store
When you open the app, tap the YouTube button.
Copy + Paste or type the appropriate link below into the URL bar
Open the video you want to watch and pause it.
Tap the play button on the bottom to get to the VR version.
If it doesn't show the video, close the video and try again.
Tap the glasses icon to enter VR mode.
Tap the arrow button to re-center.
See images below for clarifications...