Check OOTB Embed component for YouTube video integrationhttps://experienceleague.adobe.com/docs/experience-manager-core-components/using/components/embed.html?lang=en
Refer https://solutionpartners.adobe.com/content/solution/us/en/training/learning_program/learningProgram81313.htmlThis will help you to learn all new concepts of AEMAACS.
How you are associating 20 folders with image A?You need to copy in each and every folder .For pages you can check in properties reference tab it will display the list of pages where your image is in use.