Noobzilla
I Love YTtalk
Although I think the title is even more important than tags (that's just my belief, I have no evidence not knowing the algorithm).
Last year one of YouTube's partner managers (works for YouTube with a @YOUTUBE email address) and I had a ~20 minute Audience Development Hangout consultation and he mentioned that if SEO were a table, the Title & Description would be the top and legs and the tags would just be the screws. He said they were still important, but not to overthink them because the Title & Description are the main components.