Youtube makes watching stuff like this possible. Warning: once you've seen it you can't unsee it
Can you learn guitar from videos on youtube?
In my opinion you can learn lots of things from youtube guitar tutorials and lessons, but I think you also need to supplement that information with feedback from an experienced guitarist, whether that be a friend or a teacher.
From my perspective as a teacher, I think youtube videos are great,
and I absolutely encourage students to watch and learn from them.
As a beginner, they are fantastic for inspiration and to show things
like chords for songs.
And who doesn't want to watch five creepy North Korean kids
play guitar (see video)?
However what youtube videos can't do is provide
individual critical feedback and direct students about what to
focus on in their practice.
I think as you develop as a guitarist and move onto being an
intermediate level or above, youtube tutorials can be very useful
to give you different ways to look at things. By this stage you will
be more self aware and be able to put a youtube lesson into context.
I also believe that seeing a teacher can also motivate you to get better. Also talking things through with a human must be better than sitting in front of a computer screen.
In my own experience, when I first started to learn guitar I learnt from books, and very early internet websites. When I finally went to see a teacher, I realised very early on that I had missed out on some very fundamental things. My guitar wasn't even in tune for example! I found a few lessons early on invaluable and it helped point me in the right direction.
So, these are my thoughts. Hope they're useful!