Anyone trying to learn a foreign language on their own with free resources on the Internet via YouTube and other sites, will eventually run across the Natural Approach developed by Stephen Krashen and Tracy Terrell years ago. This particular video gives a simple overview, along with a great visual example of the importance of "comprehensible input" in language acquisition.
Those of us using videos we find on YouTube for exposure to our target language should keep this idea of comprehensible input in mind. There are plenty of language related videos where vocabulary is presented (sometimes even on a mock green chalkboard) as word with perhaps a sample sentence and no other input. On other language related channels, YouTubers are more likely to use images or body language along with vocabulary words a little easier to understand. It's not that I skip videos that expect me to read. As a literate adult, I can supply some of my own comprehensible input creating images in my mind. But I've definitely found some presenters are a little better at providing a richer visual and auditory environment to teach the meanings of different words.
A tip... Look for videos created for children that are trying to learn your target language. You'll find YouTube channels that adults in various countries created for kids in your target language. If their target audience is a very young child, they will use simple sentences and phrases to describe words and concepts. Adults trying to learn the language will find this helpful. Perhaps you'll find some teaching videos that supply images and sounds to go with any words or concepts.
Incidentally, some of the of the best "vocabulary" videos I've found on YouTube have been created by YouTubers with a personal channel. Translate "my room", "my iPhone", "my iPad", "my purse" or "school supplies" into your target language and you'll find some videos where young girls and women point out all kinds of great everyday items while saying the object's name. I don't post those kinds of videos by kids here as they're target audience doesn't match my interests. But, their videos can sometimes be very helpful for those of us trying to learn a foreign language on YouTube.