Don't buy Air Video until you at least try the free ZumoCast app. Zumocast is one of those game-changing apps that don't come around that often. In one fell swoop, it combines the functionality of Dropbox, Remote Desktop, and Air Video into a single app. ZumoCast gives you remote access to your entire computer so you can watch videos, listen to music, or view/manage your documents from literally anywhere with an internet-enabled computer (DRM-free content only). While at home, it can stream almost any video/audio format to your iPad and iPhone. To play your videos while on-the-go, you can just download them and play them natively without needing to convert them.
Best of all, it totally bypasses iTunes. Anything you add to your 'Movies' and 'Music' folders will instantly sync with the app. You don't even have to be at home to manage your library, you just login to www.zumocast.com from any browser and you can view, upload, and download your files from anywhere. Listen to your music online and access your files from your work computer. And for times when you don't have internet, you can download any file directly to your iPad. ZumoCast also supports multitasking for music, so you can close the app and your music will continue to play.
And it goes above and beyond just music. You can literally access terabytes of files from anywhere using any computer, without uploading or syncing them. I can't even begin to stress how powerful this is. Thank you ZumoCast!