I keep my dirty little YouTube secret relatively behind closed doors barring a select few close friends, even so I don't send my videos to them, they just know that I do it.
Reasons:
-In terms of growth I don't think it will help at all aside from maybe a few extra likes, views and 'Hey good for you'
-I'm planning on making a complete fool of myself in my endevour to YouTube so I'd rather contain it to the internet and not have everyone I know in real life know that I do it.
-Our YouTube videos will usually appeal to a particular niche audience, usually this is not the friends/family and other random people we have on Facebook, so putting our content out on our social profiles is unlikely to do much for your audience retention. (Unless you have some absolute fire video that will appeal to the masses)