If you create content on Youtube, watch people who create content on Youtube, if you interact with people on Youtube via comments or other social networks, if you have a connection to people on the website, then you are part of the Youtube community, and therefore, a youtuber.
"To me, a YouTuber is someone who part of the community of people that actually cares about YouTube and the creations that it hosts."- Hank Green
youtube after taking acid
"Youtubers has cats on treadmills"
when someone did sumthing really cool or crazy or stupid and you don't have a camera all you have to say is that it's a you tuber
damn larry papini that was a you tuber moment
one who constantly shows off for publicity as if looking to be posted on You Tube.
Omg Heather, I can't believe you just did that. You're such a you tuber!
One who wastes time watching You Tube videos (particularly when they should be working.) Computer variant of couch potato
"They gave that you tuber a raise!? Every time I pass his desk he's watching videos."
Someone who goes onto youtube, watches countless videos, and considers it an occupation.
Occupation - Youtuber (Y)
One who youtubes, or is obsessed with youtube.
Man, that person has over 100 youtube videos. What a youtuber.