Long tags or keyword tags?

[AikoMiyoko]

i always add my video title as tags and followed by other tags that are relevant. sometimes long sometimes short..i find though that longer tags help to rank your video higher.

 

[MattZ]

I'm confused by many peoples responses to not group them, the more general the tag is the lower you will rank for that tag as it will be way more common than others. E.G "Cat" Will be harder to rank higher for than "Cat goes to pet shop" If you catch my drift.