Eek. That's a terrible way to learn a language.
Y'all are gonna hate me, but I prefer the old boring style.
Grammar drills. Verb conjugations on top of verb conjugations. Compare and contrast sessions. What's similar about the second language as it comapres to the first? What's different?
My french teachers started with er verbs, then re verbs, ir verbs and irregular verbs. We learned all the pronouns, conjugations, and also had picture books full of common nouns and short stories as our knowledge progressed. There was a heavy emphasis on speaking in our fsl clsses. My teachers would speak sentences and tell the class to repeat them at first (third grade.) By 7th grade (our 4th year of french classes) we were expected to answer questions in french.
Music vids are cute and fun, but should be seen as a supplement, not the lesson itself. Those things are often full of slang terms that could confuse a new speaker.