These videos have been posted to aid your training. They are not a replacement for attending regular classes where you will be taught the correct way of performing them.
Ko Dang is one of the original 24 ITF patterns introduced by General Choi Hong Hi. But it was replaced by the General in 1986 with Juche. Reasons for this vary, it is said the General replaced Ko Dang with Juche to introduce some of the new kicking techniques in this pattern, it is also widely believed to be for political reasons which are evident in the meaning of Ko Dang.
Tae Kwon Do associations around the world still teach Ko Dang as it is one of the original 24 patterns. At Preston Tae Kwon Do you will have the opportunity to learn both of these 2nd Dan patterns, but will be graded on Juche only.