Enterprise Security and Apple TV

If your Mac is connected to the network, use Internet sharing on the Mac and connect your ATV to it. That may solve the problem.

Go to the Sharing section of the System Preferences on the Mac, set it to do Internet sharing from Ethernet to AirPort, then do the wifi setup on the ATV. You should see the Mac listed as a wireless access point. Make sure to enable WEP in the AirPort sharing options so that other people within range of your Mac can't use it as an open access point.

If you have another wifi device like an iPhone or iPod touch, etc., see if the Mac shows up in it's wifi access point list. If the Mac doesn't show up on any device, Internet sharing is probably not properly configured.

If Internet sharing is configured correctly on your Mac it should show up as an available access point in your ATV's wifi setup. However, ATV wifi is known to be somewhat flaky. Try rebooting your ATV by unplugging and replugging it, then check its wifi setup again.

When you create your ad hoc, try another channel, if you use security try 40 bit and choose a 5 character password.

other than the possibility of my university having terrible wifi...

If you set up Internet sharing as I described, your Mac actually becomes a wireless router. Reboot your Mac after you do the sharing setup and see if that makes a difference. Internet sharing in OS X works but sometimes it's a bit flaky after the initial setup.

If rebooting your Mac doesn't solve the problem, try it without WEP temporarily and see if it shows up on your wireless devices (but don't leave WEP disabled after the test). You might also try setting the wifi channels manually, but make sure both the Mac and the ATV are set to the same channel.

If there is wifi access where you Mac is, you might try going in the opposite direction. Connect your Mac to your university network via wifi, connect your ATV to the Mac by Ethernet cable, then set up Internet sharing on the Mac from AirPort to Ethernet.

Make sure your ATV is logged into your iTunes account in the iTunes store section of the ATV settings menu. It's also possible that the firewall protecting your network is blocking traffic on some of the ports needed by the ATV. If that's the case, then you would have to prevail upon the system administrator to open the necessary ports for it.

Well, it won't let me log in to my iTunes account, it says the password is invalid...which I have double-checked, and I know it is not.

If you're getting a password error, that would seem to indicate that you've actually reached the iTunes store. Can you play any podcasts directly from the Podcast menu?

And so, even though I have sync-ed my videos onto the atv, it won't let me play any of them, because it thinks I'm not authorized to do so.

Your ATV needs to be logged into your iTunes store account to authorize the files.

At this point I think I either need to somehow convince my university IT people to help me out....

If the problem is related to closed ports on the network firewall, that may be your only option.