Check NSURL for UTI / file type

This should work:

NSWorkspace *workspace = [NSWorkspace sharedWorkspace];

for (NSURL *url in urls) {
    NSString *type;
    NSError *error;
    if ([url getResourceValue:&type forKey:NSURLTypeIdentifierKey error:&error]) {
        if ([workspace type:type conformsToType:@"public.movie"]) {
            // the URL points to a movie; do stuff here
        }
    } else {
        // handle error
    }
}

(You can also use UTTypeConformsTo() instead of the NSWorkspace method.)