"You tube" doesn't mean anything in English. It's just a name they made up.
The term "you freak" is really a kind of insult, like "you idiot!" English people would not typically insert "are" in between, because it would also need "a" ("you are a freak"). Likewise, "you surfboard" doesn't mean anything in English, but that doesn't mean you can't use it, of course.
At a stretch, you could argue that YouTube means "the tube about/for you", but it doesn't mean "you are a tube" or "your tube".
My native language is not English and I don't understand very well a domain like youtube.
For example will be ok YouFreak.com meaning you are freak? (You are tube)
Or is more like YouSurfboard.com meaning Your surfboard? (Your tube)
Just to add to it...if you are having a tough time deciding over a Domain name you can try using DomBuddy ....do a google search you will find their website..which generates good domain name suggestions....