First off, if you go around tossing links into posts and putting up threads to promote them, most of the internet is going to come down on you for it. The rest will be polite and tell you the forum isn't for that.
In any case, it's just youtube. Unless you plan on being a partner your exposure doesn't matter too much, and your best bet is the "Tell a friend who tells two friends who tell two friends who tell two friends" method if you don't want people raging at you. Otherwise, try to do things that are impossible to find anywhere else or exist in poor quality. You'll garner interest just from being the best option, however steady that is.
Well, the plan isn't to "link on ALL the forums!" Just... you know... places like this, where I actually participate. I just don't want to link the videos until we feel like we've got the hang of the whole thing.