Spaced repetition systems have gotten better

Spaced repetition has been all the rage for 20 years now.

Dozens of apps, thousands of lectures, and it turns out its not really a silver bullet.

There's nothing really wrong with it, it's just that people tend to fall off the same way they do on any other education pattern.

A couple years ago I was thinking "If Google and Apple really cared about kids they would make a spaced repetition unlock system", where by you have to make note cards every week and then have to answer correctly to get into your phone. (obviously requires some bypass system, other rules, etc)

You could probably jury rig it with a popup that comes up after you unlock, but people would never install it anyway.

Spaced repetition is time-optimised, but it isn't self-discipline optimised, nor motivation-optimised. If you're limited by time, it's very efficient, but it drains motivation. If you're anywhere close to being limited by motivation (or, failing that, self-discipline), it just causes burnout and failure.

I credit Anki to my success at GCSEs and A Levels despite having a head injury, and I also credit it to me burning out so hard I took a gap year!

And I'm enjoying the gap year, but Anki made it a near necessity.

I don't understand, wouldn't it be worse for motivation to take longer to achieve the same results?

Spending half an hour mind-numbingly learning words through flashcards will teach you about as much vocabulary as an hour watching educational videos, but it'll be far less fun and you'll feel like it actually took two hours.

Keep that up every day and you'll burn out much faster with option 1 than option 2. Now, maybe you have enough motivation for that not to matter, or the self-discipline to keep going - as I did in my A levels - but don't be surprised if it kills your interest in the subject.

I‘m not super well versed in the literature but I know this has been researched, and—unless you are being hyperbolic—it completely fails the sniff test.

As OP points out, SRS is optimized for memory retention. You will almost certainly encounter many more words watching a two hour long video, but you certainly won‘t retain nearly as many words as half an hour of SRS.

Actually you can combine the two. Use the two hour long video to encounter new vocabulary in context, put the new vocabulary in your Anki deck, and review it with optimized SRS. You get the best of both worlds. As a bonus you often remember the source which will help you recall... This is actually common enough pattern that it has a name: Vocabulary mining.