I have never been a professional trader but I have worked in that area for about 5 years, where traders were around. Canary Wharf is full of contractors from all nationalities and backgrounds and many of us work developing systems for financial services. We get to see who is a genius.
I don't believe that guy is a genius. He sounds like many chavs you see in London, arrogant, cocky and certainly not very bright.
I went to his channel and watched about 10 of his videos. He can't wait to tell everyone that he is the man. On every single video he points out that he was the best.
As others have said, he had access to better prices and acted like a market maker for his clients. Like many other hundreds that work in that area. Front running people that are obliged to go through you is not a skill. It is a system set up by banks. There's no skill in that.