Playblasting shots in the Sequencer editor creates movie clips from shot cameras or from the entire sequence.

By default, playblasted shot movies are attached to an image plane on the shot's camera.
By default, playblasted movies are saved to the Movie project location. If multiple directories are specified, Maya uses the first listed location. You can change the output directory in the Project Window or in the relevant Playblast options.
To playblast one or more selected shots:
To configure settings before playblasting, open the options box next to Playblast Selected Shots.

Each selected shot is rendered to a movie clip. A movie clip indicator appears beneath each shot.
To playblast all shots on a track:
Each shot on the track is rendered to a movie clip.
To playblast the entire sequence into a single movie:

All shots are rendered into a single movie. Which shots contribute depends on how shots overlap in the sequence.
The output movie is not associated with individual shots and is not attached to any camera image plane.
To regenerate a previously playblasted shot:
Use the options box next to Re-Playblast Selected Shot to adjust settings before regenerating the clip.

When querying image planes created by playblasting, include the -shapes flag so that the imagePlaneShape node appears in the results.
string $fps[] = `listConnections -shapes 1 ($shot + ".clip")`;