https://mindfulwingchun.online
In this video Grandmaster Chu Shong Tin (CST) talks about his dilemma in trying to pass on the 'internal' and most important aspect of the art of Wing Chun! CST was teaching full-time for 64 years before he passed away in 2014 and until the end he was trying to pass on his knowledge. Known as the internal grandmaster of the art for many decades (thanks to Ip Man nicknaming him as 'The King of Siu Nim Tao'), CST was very hands-on with his teaching. He spent the last decade of his teaching solely focusing on passing on this 'Nim Tao' aspect of the art.
You can learn from his profound teachings here: https://www.mindfulwingchun.online