I used an app called Dirctr before, it provides you with storyboards that you can fill with videos you record in order to make interesting videos, that are not just long shaky plan of what's around you. http://www.directr.co/ The results are great but I've only used it a couple of times because you have to go back to the story board each time you want to add a new shot. That makes the UX complicated.

I use Vine all the time because the tap to record is the simplest way to make videos composed of several shots. You can even start recording a couple of shots, turn off your iPhone and come back several minutes/hours later to add some more. And iPhones are pretty good at focusing so it doesn't seem to me like it's a big issue.

HNers are different from most consumers, so even if it seems annoying to some of us, it probably wins by reducing ambiguity for a much larger set of users.

Obviously, it shouldn't happen EVERY time you use the app, but as an intro for new users, it seems awesome.

Are there tools like mixpanel that you could use to track engagement and usage patterns of cohorts afterwards on mobile?