These are great beginner videos. I would like to also highlight the following points:
1) on the first video at 3:50 the position of the hook (I highlight this second just to explain easier what i mean). There are plenty of mistakes what people do usually. That basic hair rig is great of single sinking bait. Still it is recommended to reel the hair rig around the hook, depends on the length of the rig. Exactly for that reason how the hook and the bait is at 3:50. with the reeling the bait will be in a better position with the bottom part of the hook.
2) the basic hair rig above can lead wrong catch in case of pop up baits. The issue is the same like at point number 1. recommended to use silicon to fix it or most of the time simple reeling on the hook can help.
3) the hook type is important as well for hair rig
4) the length of the whole rig is important as well especially with Method Feeder. Also based on the carps behavior the length can change longer, shorter etc.
5) in the US, I believe it is also recommended to use jelly wire for the rigs due to catfish and plenty of shellfish
I hope it was helpful. In case it is duplicated information just let me know and i wont write these in the future to avoid spamming
Just let me know.