iTunes movies are copy protected. If your TV isn't manufactured by Apple or your Apple TV isn't authorized by the account used to purchase the movies, you will fail to play iTunes movies on the TV directly. Yes, the easiest way is to convert iTunes movies to DRM-free MP4 or other compatible format. The iTunes DRM tool I use is named WinX MediaTrans. Powerful and easy. But be warned: decode iTunes movies when you own them, and DON'T distribute them to others.