Lol, that video is so vague. But frankly, I have no idea what to even ask. I read a guide or watch a tutorial but every single component looks different from the next (to me). Guess I'll just keep searching around.
Also what are you building for gaming, internet browsin, or major video editing n such? After that how much are you willing to spend, or how much CAN you spend.
The first thing is that plug you asked about is a floppy power plug.
Second,
the 4 pin plugs are auxillery plugs for fans, HDs, ODs, etc. You may not use them all.
OMG why did they not have that place 10yrs ago, we actually had to go to school and read!!! now 10 min''s online defeats my degree in computer scince, i am appalled!!!