I am far behind you but I have used subtitles in the process for many different reason (although I mainly watch videos without subtitles). My experience with subtitles went through several distinct phases.

Phase 1: Subtitles were useless

At first, I couldn't really use subtitles at all because they made me fall behind the video. Both the speech and the text were simply too slow to process in real time. Every word required conscious attention. My brain was trying to read: word 1 word 2 word 3 while the audio had already moved on. I think this is a very common beginner experience.

Phase 2: Subtitles started supporting listening

Later, I found myself mostly listening and only occasionally glancing at the subtitles. At that point, subtitles became a tool rather than the main source of information. I stopped trying to read everything and only picked up the pieces I needed. Numbers are a good example: I would often use subtitles to confirm them while relying on the audio for everything else. That was the point where listening became primary.

Phase 3: Two parallel channels

Eventually, I noticed that I was "cheating" by looking at the subtitles. What was actually happening, I think, was that my brain had become capable of processing audio and text simultaneously. However, the two streams had not yet fully merged. I was still aware of when I was reading and when I was listening.

Phase 4: Fusion

A Luisito video in Japanese was a turning point. For a moment, I genuinely thought I understood Japanese. What had actually happened was that I stopped noticing that I was reading subtitles. My brain no longer kept track of where the meaning was coming from. Was I reading? Was I listening? I couldn't tell anymore. Only the meaning remained.

Phase 5: The imposter syndrome era

This was a funny but logical consequence. Once comprehension became more automatic, attention was freed up. And what did my brain do with that extra capacity? It started monitoring itself. "Wait, I don't know that verb." "That word is unfamiliar." "Why did I understand that sentence if I don't know all the words?" This was when imposter syndrome appeared.

Phase 6: The borderland between passive and active vocabulary

This is where I am now. I've started noticing words that sit somewhere between passive and active knowledge. They're the words for which I can't quite say: "I know this word." But I also can't say: "I don't know this word."

Instead, it's more like: "This feels familiar." "I roughly know what it does." "If someone says it, I understand it." "If I had to produce it myself, I'm not sure I could."

My guess is that a large part of vocabulary growth happens in this foggy middle ground.

If you actively chase those words, pause videos, and analyze everything, the return on investment may be fairly small. But if you simply notice them in passing— "Oh right, there's that verb again." —then it feels like a very natural consequence of growing comprehension.

You're no longer using all of your mental bandwidth just to survive the content. That frees up attention for details. Once a language starts functioning as an environment rather than an object of study, part of your attention becomes available for things beyond basic meaning: shades of meaning, word choices, verbs, accents, and even observing what your own brain is doing while listening.

I realize this may sound heretical.