Seems like you'll probably need a 16GB Sandisk Extreme Class 10 (as the 16GB Sandisk Ultra is commonly Class 6) for the top notch 720P video, or you'll need to resort to a 24-30fps video if you want to continue using the 16GB Sandisk Ultra at the common designation of Class 6.
FYI: Class # is the Write Speed.
C2 = 2MB/s.
C4 = 4MB/s.
C6 = 6MB/s.
C10 = 10MB/s.
I'll also pull in some info from a previous help too: "
If your camera is not blinking a red non-circular icon, then it's probably the camera overheating, however it shouldn't be happening on a EOS 60D [Edit: In this case, a Rebel T2i], so I believe it is a SD Card issue.
if your SD Card is Class 4 and below, DO NOT use it to take video, it's not possible [Edit: in this case, this is not applicable]. Get a SD Card as said above with Class 6 or above, [It is commonly symboled with a C wrapped around the #6 or #10], I recommend Class 10.
The Class represents write speed, so the higher the write speed, the better performing the SD Card is during a video or photo shoot.
As a reference, the symbol is like the ones in the green circle, make sure it is #6 or #10 in the C:
*These SD Cards in the image is outdated so don't buy one of these, buy the ones on store shelves.
As a personal recommendation:
I highly recommend a Sandisk Extreme (Class 10) SD Card with at least 30mb/s write speed (Cost for 16 GB or less is below $28, black friday deals could push a 16GB into the teens so look out for deals). I had bad experiences on Transcend and PNY Class 10 Cards (the Transcend was a waste due to it being all dead and lost a week worth of shooting; the PNY decided to not work with video for about a month). "