Installing and optimizing the code to make use of the 4MB expansion pak*

My understanding, which may be incorrect, is that while one of the base optimizations he performed requires the second 4MB, most of the rest of the optimizations definitely do not.

So while I would not be surprised if he made some changes that assume more RAM is available in total beyond what was mentioned in the video, I believe most of the refinements covered could still be applied without.