Some YouTube videos say "you can skip ad in 5 seconds" . I haven't been able to figure out how to do it on the 4th generation AppleTV. Any help would be appreciated.
Using the YouTube app from the App Store? After the 5 seconds, there should be a light, translucent grey button in the bottom right of the video that says "Skip Ad".
You might consider blocking ads all together. I use an app called Weblock. It blocks ads in Safari, games, etc. I know it blocks YouTube ads in Safari, it should block them in the app to, but I'm not sure.