I think 5 weeks old might be a tad bit old to castrate yourself. Especially if you've never done it. Of course yours are pretty small, so maybe you can.
Nigerians we will do up to 12 weeks cutting. Of course that depends on the size of the goat. Teeny tiny goats we wait til closer to 12 weeks.
We do not cut anything but scrotal sac.
We also do not cut any goat under 8 weeks.
There are times when you tube videos are great but this isn't one of them. Have a vet show you. Even it it is costly it is a longer term investment.
Since you are brand new to goats it is wise that you learn from those who can teach you. Goats are like any animal they will need vet care.
Vets hate fixing stuff from clients google searches and things go wrong...