You actually are getting the hang of it. you just changed too many things each time, so your oven is giving you mixed results for every macaron. Send me a photo of your meringue and macaronage stage. This helps me decipher if its your meringue or your oven. From the looks of your macarons I believe its your oven. The initial heat of the oven set your macarons and gave macaron feet a good rise. But because the inside looks un done, tells me that there isnt enough sustained heat to finish cooking the interior. Think of scrambled egg in a hot frying pan. It'll seize and puff up fast because its heat shocked. Now if you were to cook another egg in a warmer pan. It'll stay flat. Its the same in the oven. That heat needs to stay consistent. Once the outer shell had it oven shower that outside should he set. Now the heat from the oven needs to shock the eggs in the inside so to speak I hope this makes sense. Ill be able to give you more detailed solutions. You can message me the photos or post it here in the comments.

The meringue from your video looks like it lost its structure. What type of almond flour are you using?

@Pauline Burdett try blue diamond when you bake another time. It'll change the way it looks.

I bake two at a time in my home oven. My oven is an electrical conventional heats from bottom. I leave my door ajar for a few minutes and instead of rotating you switch the pans bottom to top. I used to do it this way. Now I just leave my door open to let excess heat escape.

Thank you for pointing this out to me. Will change this. Its 32 grams of water