Copy content clipboard source to destination

Hello everyone,

I am examining code that I found here somewhere on the forum. The code copies the content of the clipboard, which is in BMP, to convert it in usable image data. 

When I look in depth at the code I am completely lost between all those different Move Blocks and got number.

So could someone explain sequentially to me how the code works and why it is done like that?

Thanks in advance,