There are several differences between the Canon 7D and the Canon T2i - and you should expect there to be simply because there is almost a 1000 dollar price difference and nothing is for free. But, I believe one difference is key and will make the T2i very difficult to use over the 7D in all but the most controlled environments.
The 7D outputs an HD stream live through its HDMI connection while recording - this allows you to use a larger, high quality monitor to pull focus. Since most times filmmakers are using these HDSLRs to capture shallow depth of field, both for aesthetics and to avoid aliasing, critical focus is very difficult to hit. With a good monitor you can do this.
The T2i had an HD stream from its HDMI port UNTIL you hit record. Then it switches to SD. And you cannot use an SD signal to get precise focus. So this camera is good for set it and forget it focus situations, such as an interview (with little movement) or other controlled shots. But nothing where you need to pull focus by using a monitor. Good to know ...