PotPlayer Playback and Resume Settings
Automatic full-screen playback
When you use Play with PotPlayer selected, Stream to 3D starts PotPlayer with its full-screen option and places the player on the display where Stream to 3D is running. You do not need to change PotPlayer's startup preference to make this happen.
Press Enter while PotPlayer is open to leave or return to full-screen.
Optional resume setting
To resume a video from its last played position, open Preferences > Playback in PotPlayer and enable Remember video playback positions:

Return to Play 2D Video in 3D for the complete playback workflow.