As the author of the video.... I would like to point out a few things.
Richard Datin's daughter actual says on page 80 of her book: "My father originally stated; 'the left side was as detailed as the right when it was first delivered before it was subjected to the changes for lighting requested by Gene."
Now those are her words, recorded in a book years before I started asking why the left nacelle was finished. A question, I must point out, that had never been asked before to any of the people I spoke with. In fact, to date, these are the only words that ever were used to describe the model before the multiple upgrades that Datin had to perform as it was filmed.
Now, people can choose to simply dismiss her statement because it runs contrary to what the "experts" say. But she was very specific about the statement. By the way, I do greatly recommend this book to anyone who doesn't already have it. In this book, you will find a great many things that Datin said about the "experts" who were misrepresenting his work. One case was Justman & Solow's Inside Star Trek; where he said "they wrongly attributed the building of the Enterprise to Darrell Anderson and his crew of model makers". He also had issues with the original Star Trek Sketchbook. And even "The Art of Star Trek" says "the Enterprise was built by Don Loos".
My point here is far too many people take what they've been told as gospel without trying to do any research to find corroborating evidence.
The folks that I checked with while researching this video knew exactly what I was trying to document and why I was trying to document it.
If you look at the model today on its left side; you will see that structurally the surface of the engineering hull has one significant design that is on the right side, but not the left - the wooden block on the right side's pennant it not presents on the left side. Even today, after 50+ years, that is the only significant structural difference that can be seen on the surface of the model.
Finally, Gary Kerr actually left a few comments concerning the video. The last one included " Btw, if you look closely at the secondary hull in the b&w 1974 NASM photo, you can see the "ghost" of the red side banner. I suspect that it was originally created using red tape, and sometime later it was peeled off the hull, leaving a cleaner, lighter-colored image on the grungy left sec of the hull."
So, in December of 1964, the 11foot model was delivered to Anderson with windows, lights, pennants, letters, and numbers painted on both side of the model. The only physical difference may have been the missing block on the left side. But even then; for some unknown reason they photographed the model from every side by the left. So, I can't say if the block was there and later removed, or if it wasn't there at the start.
I'm not an expert. You've never heard of me. And maybe no one ever will. This is not about getting "clicks" on YouTube. That assertion is offensive. I'm an aging Boomer who has already realized that we've lost far too much Star Trek history because we never asked the right questions in the past.
So instead of saying counter-productive comments like "The author says -well there's your problem". Try actually watching the video like the OP did here. If I get something wrong, then let me know. But don't pass judgement on something because it runs contrary to years of Star Trek urban legends. Do the research and ask the same questions.
Or just close this window, throw my entire response into a mental trashcan, and move on to something else.