After choosing vertices and move them on symmettry some dont want to move.
Hi Vahle,
That is one of the problems with the Editing Mirror function; if a Vertex is not perfectly mirrored (i.e: the Mesh is not perfectly symmetrical) to begin with, it won't be affected. (I never use it, so I am no expert.)
I usually just use a Mirror Modifier, it's more reliable.
I had issues with this too... see this thread https://cgcookie.com/community/12050-why-can-t-i-mirror-my-vertices
Now I have these extra vertices. I've tried to merge them by distance but I don't have any accurate results
Well, I was able to move forward. I erased the extra edges for the sake of following the tutorial as closely as possible. I'm sweating a lot on this project but I think 3d is not easy :p 
I have a problem in the course Modeling the Pot 13 min 40. When i rotate the mesh for boolean it deforms. Can fix that?
Pothead is a middle intermediate course, if you feel you're struggling, you can stop it and go to a course that takes things slower and from the start. It takes a while to build up to a comfortable position to get into a course like Pothead.
Modeling Bootcamp:
https://cgcookie.com/courses/blender-mesh-modeling-bootcamp
And others:
https://cgcookie.com/courses/rev-model-a-low-poly-muscle-car
https://cgcookie.com/courses/press-start-your-simple-first-blender-project
https://cgcookie.com/courses/tread-hard-surface-asset-creation-for-video-games
Thanks for the response. This tutorial is too difficult for a beginner; I'm stuck with the boolean part. I spend hours trying to clean my mesh, but I hate booleans so much. I'm disappointed because I'm searching for a beginner's course, and Headpot is sometimes not entirely for beginners. I'm a bit angry to begin a course and be stuck after 10 hours of hard work. I'm afraid now to reproduce this mistake. Please make sure that when a person filters courses by beginner level, they won't fall into a trap. I'm at the point of wondering if I should buy the courses one by one on Blender Market or go for the free tutorials.
I'm stuck here, probably not very difficult to fix for an intermediate user, but a nightmare for a beginner
Hey Injaw,
Martin was spot on, you need to apply the scale of the plane (Pot_Boolean).
Try stepping back, give this course a pause and take up the ones I linked you to. Modeling can be a mindbender at first, you have to get use to it little by little. It's like going to the gym and trying to lift 800 pound weights right away, when your muscles only allow you 50 pounds. You have to build up to it, take vitamins, train a lot, it's the same with Blender. So consider staying with just modeling for a while and take it from the basics with the Fundamentals and then with simpler coursers while you build up some 3D muscles.
First of all, sorry for this little burst of bad mood. Actually, it's my fault; I didn't realize that the course was at an intermediate level. Since I was progressing well, I didn't question the course level. In fact, I need to do shorter tutorials at my level. Thank you for your attention.