If you're a VSCO X member on iOS, you just need to update the VSCO app to get the new video editing feature. Navigate to the Studio in your app, tap on the announcement banner and you'll see videos from your iPhone's camera roll. You can add any filter or effect from VSCO X library as well as the standard ones from the app itself, including contrast or saturation. When you're done editing, hitting Save will put the edited video back into your camera roll (not VSCO Studio).