Through it should be noted that the valved mask where still reasonable good.
Actually even a bandanna reduced the amount of water droplets in the air by nearly 50% (if I remember correctly) or at least the one they tested did so.
But fleece turned out to be terrible as it spliced the droplets into many smaller ones without hindering them much increasing the total amount of droplets in the air.
Thinks like that are why I thing we should have a larger study with that method or similar methods.
Because we don't know if all fleece masks are as bad or even worse then no mask or if it was just that fleece mask and if therefore we need to count fleece based home made masks as wearing no mask.
(This also would mainly affect people using fleece based scarfs as both scarf and mask as well as people having a fleece based cycler mask and using it as a protection mask too)
Only gotcha it's that the study was about introducing a simpler affordable way to measure the effectiveness of masks wrt. protecting others and get feeback for that method, so the number of tests they did are to small to be anything then an indicator for what might maybe be the result in a large study using that method.