The iPad may work wonders as a mobile video player, but it's rather hamstrung by the limited number of video file formats it supports.
Indeed, unless you convert all your videos to MP4 format (a lengthy and sometimes fruitless process) or stream them via an app like Air Video (not an option when you're offline), you're sorta outta luck.
Enter CineXPlayer, an iPad video player with native support for the popular Xvid (AVI) format. It's free, and it's fantastic.
Start by copying videos to your iPad by way of iTunes' File Sharing feature (which is accessible in the Apps tab once your device is connected). It's fast and easy--I loaded a couple gigabytes' worth of files in just a few minutes.
The CineXPlayer app is about as bare-bones as can be, with little more than an alphabetical list of videos and a rudimentary set of playback controls: play/pause, volume, full-screen toggle, and a scrubber. Thankfully, it's clever enough to resume from where you left off.
Not sure how to use the aforementioned File Sharing tool? Tap CineXPlayer's Add More Movies button for a video tutorial.
I tested the app with a variety of Xvid-formatted videos, and every one of them played perfectly. Keep in mind, however, that owing to the numerous variables that go into Xvid encoding, you may encounter files that don't work. And the developer specifically notes that CineXPlayer doesn't yet support MKV video or AC3 audio.
We hope it will soon. In the meantime, CineXPlayer is a must-have app for iPad owners who want a free and easy way to watch their Xvid vids on the go.