Abbreviated notes:

Takes around 500 – 700 bags.
You need a Q sized (16mm) crochet hook
Video gives instructions to make Plarn (Plastic Bag Yarn)  with scissors and/or rotary cutter to make 4 loops per bag. Attach together using slip loops.
Simple crochet instructions – Single Crochet loosely to make 2.5 ft x 6 ft.
Edged with single crochet all the way round. Knot and weave in ends.

Tying strap – begin by attaching all the way round plus 6-8 inches (40-50 chains depending on width of roll) single crochet back and a few more single chains to strengthen and finish off.
Carrying strap – chain 50 stitches, single crochet down one side, attach, then single crochet back up the original chain stitch.