When you see Tag rankings on your video, it shows you where that video ranks in search results when a search is performed on YouTube for that keyword.
Sounds simple, right? It's not.
When we do a search on YouTube, we see different results than you do. We even see different results ourselves if we're on a different computer or different city or country. Sometimes there are different results if we search now versus 10 minutes from now. So what are the "real" results? Well, there aren't any.
We suggest you use your ranking values to gauge movement for a video (if it's going up or down in the rankings) rather than believing that the number shown is the actual ranking position everywhere in the world for everyone.