Browsing on a desktop offers a different UI/UX experience than a smartphone. On a desktop:
The 404 page can include more complex hover effects on recommended thumbnails, encouraging clicks. Video Title- Tube8 - 404 Page Not Found Desktop
If you are seeing a 404 page on Tube8 and believe it is a mistake, you can try these desktop troubleshooting steps: Browsing on a desktop offers a different UI/UX