I have had a blast doing HD video w/ my t3i, particularly w/ the 10x "sensor" zoom. I have found the 70-200 II to be a darn handy super duper zoom - something like 120-3200 (though to jump to the "sensor" zoom it requires a setting change so smooth zoom is from equiv 360 to 3,200)
I also adapted a EVF lupe with an eye piece extension (little epoxy) and can now hold the camera in a more typical fashion.
So much for the knocking around fun stuff.
Clearly (audibly that is) the microphone in the camera body is just a non-starter if one is going to do any audio that is even remotely equivalent to the images. Any thoughts on the subject?