Hi Renê

I see that you are frustrated after several years of trying. Please, do not blame the teachers. (I think you meant teachers in videos, if you also say that you taught yourself?)

This is not "fake" English, but you can say it is graded English.  The thing is, at a beginner level, there are a couple of important factors: 

1) The student needs to understand what is being said.

2) The student needs to be able to use the phrases and words.

This means simplifying. Yes, if a teacher simplifies too much then it sounds ridiculous. Even we can hear that. Then, you build on that knowledge.

It is not possible to simply give you any English and expect you to understand. It doesn't work with native-speaking children, and it certainly doesn't work with learners. So, I can only suggest some patience.  Do the hard work now and the higher levels will be easier.

Best of luck.

Hi 

I completely get what you are saying. However this is true for almost all languages. I'm an English language teacher and I always joke I know how to speak English and also English as a foreign language :) this is because natives have their own culture and cultural expressions that is almost impossible to teach in the classroom. For me in order to learn these slangs the to you need to be emmersed in the culture itself. Interactions with natives who are not modifying their English for you is key :) 

I understand what you mean. You feel you can understand your teacher and then you are in the middle of a real conversation and you don't understand anybody but apart from the fact that your teacher might speak slowly to you, you have been used to his/her accent.

Related to understand children ... sometimes they speak so fast and with a non-clear pronunciation, that it is difficult to understand them even in my own language!.

There is a lot of implied meaning in English conversation (and I assume in  any other language). Sometimes the meaning can change with the tone of the word. It takes time to build up experience. Even a native speaker might have difficulty with speaking to another native speaker and need to ask more questions to clarify the meaning. 

Would a a teacher of English teach fake English? Would a Portuguese teacher from Portugal be teaching fake Portuguese when in Brazil, the spoken Portuguese is different?

There are many different aspects to language learning. If you have difficulty  with listening to children, try to think carefully where the problem is. A second language learner of English referred me to a YouTube video of an American talk show watching a child in England speaking English. The language learner and the Americans on the talk show could not understand that child's regional accent nor the child's sentence structure. 

I learn Chinese. My listening skills are quite poor. I don't blame the teacher- I try to look deeper into the reasons (which is lack of daily input and my inexperience of the language).

Please do not be discouraged.  There are times when I listen to the news and people from a region different than mine are speaking and I can't understand what they are saying.  Also, we use a lot of slang.

When I encounter someone who is not a native speaker of English, I always try to speak at a sensible pace and I speak clearly.  I only want to encourage them and think it's great that they want to speak English.