Could you use websites and use games from them on here (with their permission). I also play at miniclip.com and i see them do that all the time, usually from nitrome.com.
Usually what happens is a staff member from a game site (I believe) makes an account on AG with the name of that site as their name. Then they take the games and upload them here. That's mainly what happens, you can't take credit for whats not yours.
Yes, ArmorGames does do this. CrazyMonkeyGames is one of the biggest contributors in AG. We also take games from Miniclip. And I think that they submit the games, we don't 'steal' them.