I don't think users can distinguish a "local" website with a public one. So this software should just come with the OS as a "movie maker" package. As mentioned Handbrake UIs are a decent candidate.
I think OSs are generally over bundling helpful software, unless its a funnel to a paid version. The security risk is too high, and so is the legal risk of anti-monopoly action ("why are you killing independent movie editor businesses?").