As a user, my personal view is that generally speaking native apps are always more of a pleasant experience than web apps. Web can give you certain benefits of a central off-site server. From your description and the description given in your product video, it doesn't sound like those particular aspects of web apps come into play for this application.
And in the case of video, you can be quite bandwidth limited. I'm not sure if I'm your target market, but I know in my case if I were working with large video files and I just need some cuts here and there, it would take me far far less time to just load up iMovie than to transfer my videos to a website.