For Canon SLRs shooting video your best reasonably priced option would be the T5i which just came out recently. It can do autofocus on the fly unlike all other Canon DSLRs shooting video.
I don't think that is totally accurate. If I'm not mistaken,the T4i shares the same video capabilities as the T5i and should be less expensive (possibly refurbished) and I think the SL1 (have seen very good deals on new) and 70D do as well. If you're getting a DSLR explicitly for video, I wouldn't get the T3i, as it lacks the touchscreen focus and STM lenses functionality which seems like a critical differentiator between the bodies listed and the T3i (which I have, btw).
One thing to consider for doing video and overcoming the 12 minute "issue" would be to install magiclantern, which apparently has an automatic restart feature or allows decreasing the bitrate to increase video length. http://www.magiclantern.fm/http://wiki.magiclantern.fm/faq#how_do_ ... 12_minutes
Honestly, I wonder if you wouldn't be better served by an HD camcorder that is build explicitly for taking video and shouldn't have any length limitation shenanigans to overcome. You can't swap lenses until you get very expensive, obviously, but it certainly simplifies a lot of things in the process.