I have been researching "TAGS" and the more I find out, the more it ticks me off. I spent a lot of time tweaking my tags over the years only to find out... they are near useless. I work for a large media and marketing company, with a large Social Media division. They told me Tags are pretty much useless, it is all about the title and description, and the viewer "friendly--ness" - AKA if you have "How to weave a basket" it will be much more likely to hit the suggestion feeds than "Titties on a hot tin roof."
Straight from Youtube:
Tags are descriptive keywords you can add to your video to help viewers find your content. Your video’s title, thumbnail, and description are more important pieces of metadata for your video’s discovery. These main pieces of information help viewers decide which videos to watch.
Tags can be useful if the content of your video is commonly misspelled. Otherwise, tags play a minimal role in your video's discovery.
Note: Adding excessive tags to your video description is against our policies on spam, deceptive practices, and scams.
