Braided rope, twisted rope, plaited rope, endless winding rope, kernmantle rope… there many types of ropes, and that’s only in the construction. There are a wide variety of rope materials, too: Hemp, cotton, jute, straw, polypropylene, nylon, just to name a few. From Wikipedia:
The use of ropes for hunting, pulling, fastening, attaching, carrying, lifting, and climbing dates back to prehistoric times. It is likely that the earliest “ropes” were naturally occurring lengths of plant fibre, such as vines, followed soon by the first attempts at twisting and braiding these strands together to form the first proper ropes in the modern sense of the word. Impressions of cordage found on fired clay provide evidence of string and rope-making technology in Europe dating back 28,000 years. Fossilized fragments of “probably two-ply laid rope of about 7 mm diameter” were found in one of the caves at Lascaux, dating to approximately 15,000 BC.
Other natural fibers can be used to create rope (some being much stronger than grass), and this method will work equally as well with any other flexible material. Grass does tend to become brittle when dry which could weaken this rope, but even then it does maintain some strength. In moderate humidity weakness from drying should not become an issue at all.
Note that for best results, each of the two tails of the rope should be twisted an equal number of turns as they’re wound. That will ensure that the two coils wind around one another tightly and in a double helix pattern. If one side is twisted less than the other it will tend to stay straight, while the more twisted side coils around it like a spring. When I first started winding the rope in the video you can see I didn’t do a very good job twisting both strands evenly for the first few inches, and one side was coiled more than the other. Try to avoid that, as it will be a weak point.
Test your rope with a game of tug-of-war or by tying a figure 8 knot.