I dont have any time today and may not for the next few.....if you haven't figured it out yet, send me a PM and I will try my hardest to get you an answer within the next week...just don't have enough hours in the day right now to even answer beyond this paragraph
Apps such as VLC and others need local video on e.g. a NAS which is in your local network. You could then store (in e.g. .mp4) your movies/tv series on that NAS and watch them on your iPad or iPhone with e.g.:
VidOn Player (free) VLC Player (free) nPlayer (4,99 dollar) Infuse3 Pro (free, but for full options you need in-app purchase of 9,99 dollar) - the best one with e.g. Chromecast support, alot of audio codecs (AC3) are supported, option to show opensubtitles.org on videos.
To watch free movies there are a few (documentary) apps in the App Store or have non-popular movies in it e.g. SnagFilms, Viewster, Big Star Movies (has some free movies).
Other then that you have a lot of paid services (9,99 dollar or more a month) such as Netflix, Hulu Plus, HBO, Showtime but it depends in which country you are what is offered. Ofcourse you can also buy separate series and movies at iTunes.