YouTube videos are already tagged when uploaded, which helps the site to serve up similar vids when people are watching. However, the site is debuting a new feature today called 'Topics', which looks to make this process more efficient. It sounds similar to tags, but the keywords are based on YouTube's own analysis of what a video is about or relates to. For example, Lady Gaga's Bad Romance video might be associated with a topic called 'Workout Song', and when that link is clicked, users will find other videos sharing this attribute.
