The amateur video shot from a ferry’s deck shows people running, in broad daylight, towards lorries waiting to board the ferries.
They are spotted by security staff that chase them away with cars and motorbikes.
Local site thebest.gr, reports that such scenes are almost a daily occurrence in the port of Patra.
It claims that a few days ago a member of the Greek coast guard was injured trying to prevent migrants from storming a ferry.
In a separate incident, the captain of a ferry was reportedly threatened with a nautical flare when he asked a group of migrants that had entered the vessel to disembark.
The western city of Patra is a gateway to Western Europe for many migrants who remain trapped in Greece.