There's a lot of machinima videos out there. Mostly done with Garry's Mod, a source engine sandbox game. Sometimes you come across a gem such as Mastermind that gives you a better idea of what a good machinima really is.
Written and Directed by Ezequiel Guerisoli, this is most certainly one of the best machinimas I've seen. It's created using the Grand Theft Auto 4 engine on PC, and visually it looks pretty amazing. There's only one episode currently available and it doesn't give you too much information as to what the series is about, but I can tell future episodes will be really enjoyable.
Don't let the use of the GTA4 engine make you think this game is has anything to do with with liberty city, hookers or anything related.