Are you actually using the phrases you're learning anywhere, or just passively watching?
Here's the thing - those short clips are decent for exposure and motivation, but they're not enough on their own. They work best as a supplement. The content sticks better than scrolling mindlessly through memes, yeah, but your brain isn't really cementing anything without repetition and active use. You're picking up vocabulary and maybe some patterns, but there's a huge gap between "I watched a video about French subjunctive" and "I can actually use it in conversation." That false confidence you mentioned is real - it feels productive because it's engaging, but passive watching doesn't build the neural pathways you need for actual fluency.
The people who actually get fluent using this stuff tend to combine it with other methods. So they'll watch the shorts, then immediately try writing a sentence using what they just learned, or find a language exchange partner and actually speak it. Or they're using apps like Duolingo or doing grammar drills on the side. The shorts alone are like watching cooking videos instead of cooking - entertaining, informative even, but you're not learning the skill until you're in the kitchen actually doing it. If you want real retention, you need to practice producing the language, not just consuming it. Even just keeping a simple journal in French or finding a tandem partner would probably triple your actual progress.