title and tags

Most of time we watch some of YouTube video show hastag on the bottom of video. I heard that, it is YouTube new search algorim or new searching rules. How can I used this types of hastag on bottom of video?

Hi I'm Thomas and I'm wondering what tips people can give on titles and tags. So far from looking around for Titles I've seen: 1-use titles that have a hook and people will want to click on, 2-use titles that match exactly what your video is about and then others 3-saying make it as long as...