We tried using a similar product a few years ago. It consisted of a set of three wool covered, soft, slightly elastic balls for use in our drier. We never noticed a shorter drying time, even with lighter loads like sheets, and there was definitely no difference whatever when we dried towels. We stopped using them, and we noticed no increase in drying time for whatever that's worth.
I'm really not sure of the physics of these balls. They didn't stop knotting and gnarling of various items. Our duvet covers still swallowed towels and our pillow cases would swallow socks and hand towels. They didn't expedite the drying process. I can't imagine how they are different from, let's say, adding a bunch of balled up clean socks or some other dry item. They might absorb a little moisture, but not all that much.
The only use for them would have been to scent our laundry, perhaps by dabbing the balls with lavender oil, but we like our laundry unscented. This product may be somehow superior to the one we tried, but we doubt it.