Heather,
Just wanted to make sure you saw Maria Miller’s recommendations for algebra after 7A & B, as there is a lot of helpful information there that is good for anyone looking at algebra options:
https://www.mathmammoth.com/complete/algebra_1.php
We are half way through 6 so we are in the same boat. Looking ahead, we are also considering Shormann Math:
https://diveintomath.com/shormann-math/
Math U See is such a different teaching style from Math Mammoth, I would think it would be a hard transition. If you are wanting a video to go with the book, there are so many out there and you have lots of time to explore your options. By the time you get to starting algebra there will probably be even more options.
Hope that helps.