What does 'YouTuber' mean?

As a YouTuber myself and brother of quite the famous YouTuber, I would say this word is definitely used more often for producers, but also used as a general term for someone who uses YouTube often. I watch and create videos a lot on YouTube so I consider myself a YouTuber. I'm not sure that I would still call myself a YouTuber though if I only watched videos and didn't involve myself in the community.

At VidCon most creators are called YouTubers or Vloggers.

Also doing a Twitter search for #youtuber results in famous YouTube creators or new creators looking to gain subscribers/announcing their channel.

Here is also a list of YouTubers, which is a long list of popular YouTube channels, not viewers.

And here is a video about HOW TO BECOME A YOUTUBER, which is not about how to watch and comment on videos, but about building your YouTube channel.

This answer should be considered supplementary to @Michael Rader's which, in my opinion, correctly explains what the term YouTuber means today. The following is a small attempt to trace its history via UD

Don't knock Urban Dictionary, it has its flaws but it also records when people posted their definitions and the number of readers who agree(d) with them.

Let's look at some of the older definitions (the emphasis is mine but the spelling inaccuracies are all theirs.)

• someone who is a member of the youtube community.
  BTW: if you know what urbandictionary is and not youtube, than you better ask somebody.
  NBC is asking all you youtubers out there to make a clip for the office.
  _{di uh yeah 20 luglio 2006}

• Someone who uses the site youtube.com to post video blogs, videos, and such.
  Go to youtube.com/paperlilies
  John is a youtuber, always posting funny videos on youtube.
  _{di LadySango 21 novembre 2006}

• A person that watched more than 10,000 videos on youtube
  Hey, you just watched more than 10,000 videos, you must be a youtuber
  _{di Basco selanikio 04 giugno 2007}

• 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”
  _{di larry papini 03 agosto 2007}

• One who youtubes, or is obsessed with youtube.
  Man, that person has over 100 youtube videos. What a youtuber
  _{di ritzel 02 marzo 2008}

• 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." _{di namowal 25 ottobre 2008}

• Someone who spends there life on youtube and has over 1,000 videos and has watched over 1 million.
  That youtuber has no life and no friends.
  _{di AD Montgomery 01 gennaio 2009}

• Someone who goes onto youtube, watches countless videos, and considers it an occupation.
  Occupation - Youtuber (Y)
  _{di Act Like a Clown 17 maggio 2009}

• A person who has over 500 favorites and has watched more than 10,000 videos on youtube. A.K.A., Matt Thomas.
  Matt Thomas, youtuber _{di Slave on Dope 18 maggio 2009}

• Invariably semi-literate and abusive, often racist and/or pervesely [the irony] sociopathic moron.
  The bus got held up by some total YouTuber yelling at the driver.
  _{di FelixTheRat 22 ottobre 2010}

The first and second definitions both posted in 2006 are respectively the second and fourth listed by Urban Dictionary. The total number of users who agreed with these two definitions are 664, those who disagreed are 263. Now, I don't know if there is a way to see the voting patterns, if the number of voters who disagreed grew as the years passed by or vice-versa. If there is a way to see when UD users voted that would present a more truthful picture.

Nevertheless, I am old enough to remember when I first visited YouTube and it was mainly to watch old music videos, a trip down memory lane if you will. Afterwards, I would watch the funny videos uploaded by anyone who had a fancy video camera or digicam (nowadays with the latest smartphones anyone can post a short clip of a friend slipping on ice, but then, it was still seen as a novelty.) The terms Vlogger, derived from blogger, and YouTubers that we are familiar with today, between the years 2005 to 2008 were relatively unknown to the general public.