I've never used the stuff from Josh's that you've linked too but always preferred a fabric product to the fiberglass screen. It folds around corners easily, never has any sharp pokey bits, much nicer to cut and work with, and you can easily line not only the hydroton layer but also fold it to go an inch or so up the glass (however deep your substrate is) to hold the substrate in better.

It comes in a few varieties. The kind I use is more on the flimsy fabric side compared to some of the plasticy feeling heavier duty stuff used in landscaping especially where you'll have foot traffic. The flimsy fabric kind is more than durable enough for a vivarium as it likely won't be subject to a human foot.

You can get small rolls at the dollar store and some garden centres will sell it from large rolls cut to the length you want for pretty cheap. Home Depot and other stores will also have rolls of it that are reasonably priced for what is likely a lifetime supply for the vivarium maker.