I have a website talking about my country. I came across a vlogger who posts videos on youtube almost every week and talking about my country. He told me he can add links to my website in the video description. Will this help me in SEO ? I know it's the case if I published new videos myself but here it's about videos that might be few weeks to several years old...
If he says he can do it and the videos still get hits even if they do not help seo of your site they might drive traffic and that is why you do seo so i would try it.
If you can make videos then seo them and link to your site also. Just try different keywords than any video that has your links already
In theory, it might help if YouTube allows you to leave such links. But as far as I know, it automatically removes them. But you can try, of course. Most likely you'll need a very good profile and many years of using a particular account. So the only way is to do it from your own personal account. But I'm not ready to set it up if I get banned for it. BUT! it might work for platforms somehow related to YouTube, like "YouTube to mp4 converter" or something like that.