Mac: default app to Open a movie file

I am developing an Mac Desktop application that records a screen in mp4 format; It can also play mp4, mov format videos. So, 开发者_开发技巧I have given mp4 and mov formats as supported document types in info.plist. Now, if the user installs my app and opens info window of a .mov/.mp4 file, my app will be listed in the popup provided for 'Open With'. My intention is just to list my app in that popup. But, some users complain that MyApp has become the default app to Open With even if they have not done it manually. They do not remember when the problem started (AFter recording through my app OR just after launching my app)

Does anyone knows if info.plist settings OR any API has caused this problem?

Sadly, it sounds like the way in which Launch Services makes this selection is publicly unspecified and prone to change: http://developer.apple.com/library/mac/documentation/Carbon/Conceptual/LaunchServicesConcepts/LSCConcepts/LSCConcepts.html#//apple_ref/doc/uid/TP30000999-CH202-SW21

There's very little to tweak.

I think, but I am not sure, that Editor role applications are preferred over Viewer role applications.