You really really don’t need photographic memory for this. I assume you read the article. Now just create a new repo and go explore the .git. Things from the article will immediately make sense. You immediately get a very intuitive understanding of tags, branches, heads, trees, commits etc. Then just give it a rest. Come back after a few days and try it again. After a while, it will be better than any photographic memory.

I wish I had photographic memory

I wish I had a pornographic memory when reading stuff like this. Would save loads on, uh, monthly service fees.