It was gone as of 2014(or so, someone correct on this).
you can still try the trial for Cevio Creative Studio S
(or find someone with the install program for the old free program)
I mean, Dailymotion is another service i can name on top of my head. but it's mostly used for uploading things to avoid copyrights' eyes. (cough anime openings)
but other than that, I'm afraid you're out of luck :/
also i don't ever think there was a proper tag system on YouTube in the first...
Has been bothering me recently:
Kid: "How do you do this thing?"
Me: "<explains said thing>"
Kid: "<ignores>"
Some other Kid: "<explains said thing>"
Kid: "Oh ok thanks"
Me: :^)