I had to watch those videos a couple of times before I understood. After you have learned how to do both 2 and 6 edges at a time, experiment/practice with them a lot and then decide when to use 2 at a time or 6 at a time.
2 at a time:
- A little more moves
- A little harder to find edges
+ You get 1 free edge (3 at a time) quite often
+ No weird cases
6 at a time
+ Less moves
+ Easier to find edges, especially after the first 6 because they cannot be at the back
+ Sometimes you get 1 free edge (7 at a time)
-More often you get a bad case (5 or less at a time) which ruins the flow and makes pieces hard to find
You can also check this video, where I use the 2 edges-at-a-time technique on the 5x5x5. I explain a fail-safe method for setup-moves there. I will make a speed-optimized version next weekend. If you would like, I could make a video for 4x4x4 also, but I think the existing videos are good enough already.