This is mostly okay advice for beginners, but as you get faster and want to improve your efficiency further, there's a lot of freeform blockbuilding tricks you can use.
Like, your solution to the last two bars at 2:45 in the video took 20 moves, but there's
an 8-move solution (!!) that fully exploits the pre-made blocks. (Not that I'd have figured that out in a real speedsolve, though.)
Also, rather than strictly going left to right, you can do the bars on the left side in any order; usually going from middle to left then extending that block rightwards is better, since it reduces the need for slice moves.
Edit: Also, doing the middle bar on 7×7×7 first has a huge advantage even beyond reducing slice moves. You have freedom to adjust the front face however you like, which gets rid of some really nasty middle-bar cases. The middle bar on the odd big cubes is special, since it's the only one that consists solely of t-centres; the rest of the bars are a mix of t-centres, x-centres, and obliques.