A lot of times you can find videos geared towards beginners. Japanese has podcast style and interview videos. I've seen street interviews for Spanish. There are channels dedicated to creating content geared towards learners/beginners.

If you don't understand anything at all, I would personally not recommend watching video content in the target language. Some people argue you still benefit by listening to how people speak, and that is true to an extent, but it's also frustrating to watch something and not understand anything. This may lead to you feeling bad about learning the language and you never want that.

No, you generally should not study subtitles or memorize them. The idea is to get accustomed to listening to the native speakers of said language speaking it, even though you will undoubtedly miss some of the meaning.

I watch videos in Japanese without subtitles and gather the meaning by the context.

If you’re learning English, I would specifically check out the BBC learning english videos. They have a website and also a ton of content on Youtube. You can also search specifically for ESL videos. Just pick an interesting topic and search it like “Travel ESL”. Even better if you can add a level like B2 etc. Once the videos geared at learners feel easier, then you could move to broader content that interests you. I would recommend once you do that, watch in the target language with subs in the target language. You could try slowing them down at first as well. Watch once and see what you understand. Watch a second time pausing to write down new vocab and grammar and questions. You don’t have to write down every single word or structure, just try to get those that seem most relevant to the video/content so you can understand. Then study what you’ve written down, try to answer your questions, etc. and return to the video again to see what you understand more.

Actually if you are listening to what people say without understanding you will eventually understand.  If you can if you are a complete beginner don’t just listen like don’t listen to podcasts yet,just watch videos,movies,cartoons or whatever because you will understand the context and you will get some words from body language,intonation,people pointing at things etc 

Watch seinfeld

Start with watching with your native language subtitles on, so you are reading in your language and listening in the other language.

The key is that, if you want to improve your listening skills, you need to understand at least some of what you hear. In an ideal world, you should probably find shows that have relatively simple language, perhaps even shows that you have already watched in your native language. For example, the Simpsons is a cartoon that has been dubbed in many different languages, so if you have already watched it then you already know what the story is and you can try watching the episodes in English. The main idea with watching any type of videos, movies, tv shows and so on, is that you will hear examples of words being used in context, and if you understand enough words then your brain can fill in some of the words you don't know using context clues.

In language teaching, the "target language" refers to the grammar point that you're teaching. So for example, in a recent lesson about using "used to," with the context being a visit to the doctor, the target language would be "used to" for talking about past habits, healthy and unhealthy."

But from your framing of the question, it sounds like they're using a more layman's definition of "target language." So, if you want to learn English, watch videos in English, if you want to learn French, watch videos in French.

I mean, you can listen to movies or videos in English with subtitles on, and listen to the prosody of the language - the way it sounds. You can pick up phrases if you watch the video repeatedly.

So there is the ALG method where you watch videos without any subs but it is very important that you watch curated graded videos from beginner to advanced.Sites like dreaming Spanish cater to this taste of language learning.Evildea from utube is doing an experiment with this method and reports every 50 hours or so on how effective this method so far he is up to 600 hourswith using the alg method with spanish.

most people first build a basic vocab using their favorite app or methodology then start watching tv series or listening to podcasts with subs in their target language .Starting with kids shows or podcasts designed for beginers then moving on to more difficult material.Most people do this primarly to build their lsten skills but ofc it help in other areas

most language learners do a mix of reading, listening,writing and speaking.If all you do for example is get good at listening and reading then your speaking and writing skills are going to suck.

I like to read a favorite book or watch a favorite movie translated/dubbed into my target language. That way, I already know the plot and can just try to absorb the language.