Nice tutorial! I use A, A7, D, D7 or C, C7, F, F7 progression and whisle melody. I like version with 7s between chords a bit more, its has a little twist which i really enjoy!
focus on playing one chord for a few minutes then try and switch to the next chord slowly. making sure your finger placements are in the right spots. try slowly switching between those two chords for 10-15 minutes and then switch between them faster and then faster. That helped me when I was learning :)
So are we not gonna talk about how the strumming pattern is the same pattern as somewhere over the rainbow by Israel Kamakawiwo'ole? No just me? Alright.