If not replacing bridge pickup, skip between 3:54-7:03 back to guard replacement.
Pickup Routings for Fender Strat Bodies - Most Standard Stratocasters are routed under guard for HSS (humbucker Bridge) Some are routed HSH. The Strat in this video is a Deluxe Strat body and is HSH. Classic series Strat bodies most are routed SSS. Only you can know 100% if a Neck humbucker will fit by taking out some guard screws and peeking under the guard O_O
How to easy connect the split humbucker coil to get the traditional in-between quack in 2nd switch position using what is already inside your strat wiring components, see Humbucker Auto-Split coil