The purpose of this exercise is to assist you in making smooth chord changes. Take 2 chords at a time that you are having trouble with and work on switching between those two only. Go slow, learning to change chords smoothly is a process, it does not happen right away. Keep at it consistently and in no time you will be switching all of the open chords effortlessly.
In the video the chords and strumming pattern used are:
- G - Em - C - D
- Down - Down - Up (strum open strings)