I’ve actually been using a similar method for a few years, and it works as long as you have enough room to roll the top down a few times. How full the bag can be depends on the bag and its width, though.
Difficult to describe without showing it, but the main difference with the method I’ve been using is that I don’t fold the corners in first - I roll the top down a few times, and then fold about an inch of the roll in from each side. Then I slightly unroll the roll, turning it sort of inside-out over the folded-in bits (roughly the same motion as shown in this clip at the end) to lock it all together.
It’s particularly useful after parties and such, when there’s usually leftover snacks that need to be put away and either no clips, or not wanting to use clips due to the bags being destined to go home with various guests later.
