Can I watch my movies collection on my computer through Apple TV without using iTunes?
You can use Netflix on the Apple TV, or one of the other included services. You can also stream video from an iPod, iPhone, or iPad. Without a hack there is no other way to get video on it.
Only if you jailbreak your apple tv, then you can install something like Plex
Hello, apparently apple TV can only read files using itunes. If you are interested in possible work arounds you could read the content of link below. Try doing it with one of your movies and see what happens. It might give you some ideas about how to accomplish what you want: