Nifty little vid. Good careful teardown and reassembly, complete with gloves.

Couple of small cavils, though...

There are a few mistakes in there to point out.

* The OS that came with it...

The original 'Strads came with _two_. Digital Research's DOS Plus:
https://en.wikipedia.org/wiki/DOS_Plus
... and MS-DOS. DOS Plus was very obscure -- the only other machine I know to come with it was the Acorn BBC Master 512 -- but it was a forerunner of DR-DOS, which was a huge success and much later became open source.

* That isn't WordStar they show.

Well, it sort of is, but it's not the WordStar that they correctly describe as the leading DOS wordprocessor until WordPerfect came along.

Amstrad bundled a special custom wordprocessor called WordStar 1512. This is a rebadged version of WordStar Express, which although it came from MicroPro Corp, is in fact totally unrelated to the actual WordStar program. The rumour was that WordStar Express was a student project, written in Modula-2. It is totally incompatible with actual WordStar, using different keystrokes, different file formats, everything. But it did allegedly get the student a job! It didn't sell so Amstrad got it very cheap.

https://www.wordstar.org/index.php/wordstar-history

* WordStar was originally written for CP/M and ported to MS-DOS, meaning that it didn't support MS-DOS's more advanced features, such as subdirectories, very well. MicroPro flailed around a bit, including developing WordStar 2000, another unrelated program that looked similar but used a totally different and incompatible user interface, thus alienating all the existing users.

(And WordStar users are almost fanatically loyal. George R R Martin is one -- all of "a Game of Thrones" was written in WordStar!)

After annoying its users for so long that various companies cloned the original program, MicroPro eventually did something marginally sensible. It bought the leading clone, which was called NewWord, and rebadged it as "WordStar 4," even though it wasn't derived from WordStar 3 at all.

So what Doris had there is a shoddy alternative app from MicroPro, and a better 3rd party alternative that in fact later became the "real" product.

* Locomotive BASIC 2

This was sort of a sop, a bone thrown to Locomotive Software who did almost all the original Amstrad CPC and PCW 8-bit business apps. BASIC 2 is pretty much totally unrelated to, and incompatible with, the ROM BASIC in the CPC range, or Locomotive's Mallard BASIC for the PCW, but it was written by the same company. It was the only high-level language built for PC GEM, I believe. It was sold on nothing other than the Amstrads and so disappeared into obscurity.

IMHO, rather than BASIC 2 and the fairly awful WordStar 1512, Amstrad ought to have offered LocoScript PC, the DOS version of the Amstrad PCW's bundled wordprocessor. This was a very good app in its day, one of the most powerful DOS wordprocessors in its time, with advanced font handling and very limited WYSIWYG support.

* No RAM expansion in the 1640.

That's a plain mistake. There's no expansion possible. The 8086 can only address 1 MB of RAM, and the upper 384 kB of that space is filled with ROM and I/O space in the PC design. 640 kB is all an 8086 PC can take, so there is no possible expansion. Thus, no point in fitting slots for it.