A bag forming apparatus and method with single drive unit operating a drive roller and a cross-cut mechanism with the drive motor assembly being internalized within the drive roller. The apparatus is particularly designed for feeding, solely through use of a full film width contact drive roller, film material derived from a single supply roll of two ply film material. The arrangement avoids tracking problems, as well as any requirement for a supply roll driving, braking and tension monitoring. The supply roll can be laid in position on underlying, passive support rollers prevented from inertia induced over-rolling by a passive friction device which tension in the film material being fed between the single, cylindrical drive roller and an opposing pair of spaced, driven rollers in a pinching relationship with the film material being fed past the drive roller. The apparatus and method features easy slide in, slide out edge sealer and vent hole former inserts that are held by, and move with, the bag width adjustable driven rollers. The edge seal inserts feature a heating element that is compressed against the film material by an internal bias in the edge sealer. The heating element can be a a plug-in heating unit easily inserted and removed from the remainder of the insert. The cross-cut device is swung into a film material pinching position with respect to the drive roller by a drive transmission assembly and, upon return to a stand-by state, the cross-cut device automatically separates the completed bag below and partially completed bag above the cross-cut/seal. The bag forming apparatus of the present invention is particularly well suited for use with a high speed, high volume foam dispenser.