This app was mentioned in 4 comments, with an average of 1.00 upvote
There's also these apps which show words one by one that speed up the process a lot. Like
https://play.google.com/store/apps/details?id=com.vteromero.app.fastreader
Just FYI, reading 3 words at a time is probably too hard. Try just 2 -- look at a word and also read the word to it's right, then skip over to the next word. That's a good trial run, but you want to get to reading both left AND right, and you also want to increase your window size over time. (more words left and right. Doesn't work for supercalifragilous though.)
OK, here is just one of many forced-reading programs. You place your eyes in the center of the screen, and it "moves" your eyes for you. You start out slow to get used to it, then crank up the speed. At some point your mind just can't handle the speed vs sub-vocalization and just gives the latter up. It hurts a little right before this happens though, but the software won't slow the speed down.
Also you can look up spritz (software, more) but the official app wants monthly money ($3) Also, spritz complaints and more. Back in class we also took comprehension tests before and after -- reading faster "just to get to the end" is worse than not reading it at all. As I remember they'd figure out your speed/comprehension level and crank it up juuust past where you were to make you struggle. (If you're not hurting then you're not getting your money's worth! :-) )
I know that I don't speed-read all of the time and sometimes I can still hear the voice in my head. But when I notice, I'll switch back. Depending on the text, I'll read an entire line in 1-2 fixations and switch back to the video with a quick flip-down again when it changes.
Good luck! It's not a one day thing, it takes time and effort but you can use it in LOTS of other places. And for hard stuff you can easily stop using it.
I don't know which one is best, but I use
https://play.google.com/store/apps/details?id=com.vteromero.app.fastreader
there's an app called fast reader on android that does this perfectly.
https://play.google.com/store/apps/details?id=com.vteromero.app.fastreader&hl=en