That's a good video. I'll address the conclusion first.
The main reason why spelling reforms succeed or fail is because people adopt them or refuse to do so. That's directly related to the presence or absence of authoritative organs, such as the RAE (Spanish), ACL and ABL (Portuguese), Crusca (Italian), etc. English has no such organ, so it's harder to convince its speakers to adopt a new spelling. Harder but not impossible - as the video itself shows, sometimes you see grassroots changes, as messaging spelling (u wot m8?) shows.
Furthermore, a lot of those reform proposals fall to a trap called nirvana fallacy - they try to address every single issue with the current orthography at once, so they create a new system that speakers need to learn alongside the old one, at least for some time. Of course they'd resist.
In the meantime, gradually addressing small issues works way better. From my anecdotal experience as a Portuguese speaker (PT underwent a few recent orthographic reforms), resistance is mostly "angry man screams at cloud" tier; and even if you don't learn the "old" system, as long as the changes are gradual, you can still read content in it just fine. And no, you don't need to rewrite books, I got a few of them from a century ago and I can read them just fine. (Sure, after enough small reforms you do need to readapt them, but you'd need to anyway - not because the spelling changed, but because of the grammar and vocab.)
A lot of the video calls the spelling "language". While you can handle the written language as its own thing, aside from the spoken one, for spelling purposes it's better to see the written language as a rendition of the spoken language. At least when using alphabets, abjads and similar.
And I'm fucking glad the video, in no moment, uses that "think on the Cockney speakers!" strawman - because a good orthography can address dialectal differences through diaphonemes. (Before someone mentions Scots, I feel like it's probably better spelled through its own standard. This also helps a bit to preserve the language's identity as something aside from English.)
Around 3:30, the video mentions the "short vowel, double the consonant" convention. Note this convention exists also in German; I think it's inherited? (I'm not sure.) IMO a good orthographic resource but on its own it has a few problems, like:
- unavailable for ending vowels
- it tends to be unnecessarily verbose; Orrm's orthography shows it rather well.
- in some cases doubling the grapheme associated with the consonant changes its value, like ⟨ss s⟩ for /s z/.
- Middle English short/long pairs drifted away; see e.g. see "mate" /m:atə/→/me͡ɪt/ vs. "matte" /mat:ə/ → "mat" /mæt/. That further complicates any approach deciding a consistent way to spell those pairs, specially since it seems contemporary English is handling some of those diphthongs as normal vowel-semivowel sequences.
In German this rule is supplemented with ⟨h⟩, ⟨ß⟩, and vowel doubling. Perhaps it's worth to check if English couldn't borrow some of those conventions.
The "silent e" convention is not bad, though. It could be handled better, if non-silent ⟨e⟩ was consistently distinguished. (The diaeresis works wonders for that.)
So why didn't his system catch on?
Additionally, note Orrm's work is from the XII century, and handwritten conventions of the time discouraged huge sequences of vertical strokes - like the ones you'd get from lots of doubled consonants. It's roughly for the same reason a lot of orthographic ⟨u⟩ was replaced with ⟨o⟩ (see ⟨love⟩, ⟨come⟩, ⟨people⟩).
Thibaudin
That's a case of "excuse me sir, this is a Wendy's". Annotating vowels by their precise phonetic quality is useful if you're studying them, but when you're handling a practical orthography a certain level of abstraction is required. Specially when you consider those vowels might vary dialectally.
Webster
Remember when I said "as long as there's some authoritative organ behind it"? Well. That's an example. Guy was considered an authoritative organ for some, but not others; creating a standard difference.
In Portuguese you see something similar; speakers in Brazil following the ABL standard (Associação Brasileira de Letras, Brazilian Academy of Letters), while most others follow the ACL standard (Academia de Ciências de Lisboa, Lisbon Academy of Sciences). There are some attempts to re-merge the standards, but... I won't mince words, the ABL is incompetent and the ACL doesn't look specially more competent either.
Franklin
"Restart from the scratch" approach. Including new letters. Bound to create too much resistance.