I used to read speed reading books a lot when I was a kid. I thought a miracle could happen and I could read text books like history books for school really fast (I hated that reading!) But I realized it has more to do with how slow my brain comprehends plus picking up just enough hints on the parts that matter so you can skip over most of the parts that don't.
All that said, I do think the ideas can really help one learn to read faster and get good at skimming unimportant text. I probably devour stuff faster because of it, and if I remember right, one of the things you practice is not getting slowed down by certain passages of text. You're supposed to keep moving. Not practical in the real world, but I guess it helps you to learn the skills.
An autoscroll annoys me for novels because I want to skim some parts and be slow and careful in very interesting parts while my brain absorbs and enjoys it. I also find myself thinking about something else at times and then I have no clue how far I've gone since I zoned out. (Of course I do that sometimes even when I'm turning the pages manually!)
Am curious how many people actually use autoscroll on eBook readers, or if it's more of a marketing thing.