Modern Family pretends to be reality TV show as emphasized by erratic and nauseating camera movements. However, a cameraman can film from within the scan room while the MRI is operating. This is something the MR Radiographer specifically forbade ("no other people except the patient").
When Cam has his MRI and Mitchell makes his feet touching contraption, the door to the MRI machine is open.
MRI rooms have a large heavy duty shielded door that must be closed when machine is in use.
When an MRI scan is taken of Cam's head, it is not fixed in position. Without a helmet-like coil in place he can (and does) move his while in the tube. However, to obtain useful imagery, the scanned parts need to be secured. Any trained MR Radiographer knows this.