If you want to upload a file with CodeIgniter you should read my old post about it first. Setup the Config Arguments. Add the mime type mp4 to CodeIgniter.

Speed Up your CodeIgniter websites with HTML output and Gzip compression.

Upload multiple images in one same form is not that simple. You need to initialize the upload or the resize if you want to Resize Multiple Images with CodeIgniter.

Use direct database Update instead of Model to increment a field +1