thank you for feedback.
We have some requirements for porn tube, and for now retube is only one, which is suitable. You can put a multiple tags right now, we have more then 10,000 tags in our DB with more than 20,000 videos, and it's more then 300,000 relations between them. But our relevance algorythm is not so cool, we will make it better soon. Right know we're making mobile app and fully concentrated on it.