I just got a new mac air and apple tv. i have all my movies on my external usb. DO i need to convert themall to .mov or a compatible format or is there an easier faster way to watch them vis apple tv?

Welcome to the Apple community.

Without knowing what format your movies are in, I wouldn't know whether you need to convert them. You will need to add them to iTunes though.

Video formats supported by the Apple TV.

• H.264 video up to 1080pp, 30 frames per second, High or Main Profile level 4.0 or lower, Baseline profile level 3.0 or lower with AAC-LC audio up to 160 Kbps per channel, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
• MPEG-4 video, up to 2.5 Mbps, 640 by 480 pixels, 30 frames per second, Simple Profile with AAC-LC audio up to 160 Kbps, 48kHz, stereo audio in .m4v, .mp4, and .mov file formats
• Motion JPEG (M-JPEG) up to 35 Mbps, 1280 by 720 pixels, 30 frames per second, audio in ulaw, PCM stereo audio in .avi file format