Not a video course, but this one has been very popular for a long time: https://blog.miguelgrinberg.com/post/the-flask-mega-tutorial-part-i-hello-world More on reddit.com

Sounds to me like a bunch of mid-level guys tried to have a dick measuring contest and you made the mistake of trying to learn something. Plenty of sites run on Flask and Django. EVERY architecture has strengths and weaknesses. An experienced architect will choose the right technology for the needs of the project. That is all that matters. More on reddit.com

In this context, by JavaScript, you're really talking about Node. Without further context, though, there really isn't any compelling reason to choose one over the other. Here are some considerations, in no specific order. Node is built from the ground up to be non blocking. This is why it can be perceived as faster, especially for single threaded application. Every request you make is async by default. This is optional in Python. If you're accustomed to "blocking" languages, it will take some getting used to. You can famously end up in "callback hell" if you don't account for this. Modern Node supports TypeScript, which is arguably more robust, or at least more cohesive, than Python's typing libraries. Typing is either a pain in the ass or crucial, depending on your needs. With Flask, you'll have to contend with WSGI or ASGI if you want async, which requires nontrivial configuration. If you're just building a REST API, you may want to look into AWS API Gateway. In simplistic terms, this is Flask as a service. Then you can answer requests with Lambdas, which can either be pure Python or Node. You could even alternate between the two depending on the request; though, I wouldn't recommend that. Although you'll find benchmarks all over the place comparing language performance, it's not meaningful in real world applications. 99% of the time, your bottleneck will be I/O, likely from a database, not your language. But if you really want to butt heads on the performance argument, Python supports multi processing, multi threading and async, while JavaScript is strictly async. From a stability standpoint, Python versions have fewer changes and fewer versions. This can help when you're seeking answers to questions that may have been answered years ago. Made a mobile app with Python and turned out to be garbage compared to using Kotlin Yeah, mobile apps are an entirely different ball of wax. Especially given Google's endorsement, it's difficult to make arguments for other languages on Android. More on reddit.com

Yes its worth learning and no you wont have to re-learn fastapi because if you learn flask you can easily get into fastapi or django for that matter in a few hours so 95% of what you learn with flask will be reusable with any framework. People here often pose the question like its some big life decision but in reality which ever framework you learn you will be able to adapt to all others. More on reddit.com