Yes YouTube is the 800 pound Gorilla, and yes it receives the lions share of the traffic but other sites such as Metacafe, Viddler, Dailymotion and Break can still drive considerable laser targeted traffic to your site.
Consider the screenshot below for my video for the keyword phrase 'john mcenroe tennis tantrums'. Notice that the same video posted to YouTube, Break and DailyMotion are all appearing in the #1 position in Google for that term.
No this is not simply a case of upload the video and they get #1 position... my point here is simply this... NEVER focus exclusively on YouTube..
Yes its the most important site, but go the extra mile and you will boost your traffic potential.
Remember your competition are lazy, you take the road less traveled and you will get to your destination long before the others.
Also take a look at niche how to video sites such as videojug, seriously untapped markets there....