NASA

Be clear and concise. The description should give viewers a good idea of what the video is about, without being too long or detailed.
Use keywords. The description should include relevant keywords that people might use to search for the video. This will help people find your video when they're looking for information about space exploration or astronomy.
Be engaging. The description should be interesting and informative, and it should make people want to watch the video.
Use hashtags. As I mentioned earlier, hashtags can help people find your video when they're searching for information on social media.
Here is an example of a description for a NASA video about the James Webb Space Telescope:

This video takes a look at the James Webb Space Telescope, the most powerful telescope ever built. The telescope is designed to study the universe in infrared light, which will allow it to see objects that are too faint or too distant to be seen by other telescopes. The video also discusses the telescope's mission and its s clear, concise, and informative. It includes relevant keywords, such as "James Webb Space Telescope", "infrared light", and "universe". It is also engaging and interesting, and it makes people want to watch the video.