Please read the below post in a conversational tone, not an agressive or snitty tone. I intend it to be a friendly sharing of supportive information.
The doctor in the video is a highly respected exotic vet in Houston and sees many rabbits in his practice. He's very conservative in his diagnosis and treatments. I know him, personally. I did the video taping and editing. And I uploaded it to YouTube, with his permission, of course. If you were to watch the other videos I've uploaded, you'd see my two rabbits, Pixel and Skyler.
Even though your rabbits may not come into direct contact with the sawdust, it's the fumes that the rabbits breathe when urine mixes with the sap in the sawdust that causes liver damage. Especially if it's pine sawdust. There's no way to protect the rabbits from breathing in the fumes. That's why the litter needs to be kiln dried if it's a wood based product.
Again, please read this as a converational sharing of information. I know you love your rabbits and want to do the best you can for them.