Maybe. I think there is a value running a 5-10 seconds show. It's supposed to be funny, capturing attention. Youtube to me and possibly to many people is formal, it's a website you go to for a full talk. You would watch a 5 minutes show instead. This is why you don't blog on twitter. You write status and you chat and that's "blog" for some people.
Since vine is a twitter company, I am sure twitter is trying to monetize it.
5 seconds is about how long it took to read this sentence and move your eyes to the next one.
The problem is, a video, unlike a picture, or indeed - text, doesn't linger on a frame naturally.
Your example seems to support my point more then undermine it too - you mention 5 minutes. Not 5 seconds. 5 minutes is a lot of content's length on YouTube. Its not remotely possible on Vine.
Since vine is a twitter company, I am sure twitter is trying to monetize it.