Same here - my phone is over 2 years old and both adhesive strips broke when I tried to pull them out. This step looks so easy in the video, but it became the most difficult part of this repair. I ended up slowly working strips of plastic under the battery to release it. Someone mentions using a credit card, but I have no idea where you would insert that (without bending/destroying your card).
Anyway, I worked strips of plastic under the battery and used the pry tool and spudger to lift the battery as I did this. The battery bends/deforms while you do this. I was worried that the battery would internally short and heat up, but it didn’t….. just don’t go crazy bending it, and be careful where you pry (so you don’t damage the electronics/switches).
Someone also mentioned using a warm face towel - looking back I wonder if this would have helped, since you could rest the phone on the warm towel while you do this (and keep that adhesive warm the entire time). I
This metal bracket snaps over the plug, and there appears to be a snap detent on the front of the bracket (side facing the charging port). The first photo for this step show the spudger on the side closest to the battery (above the holes in the bracket). I would recommend pulling up on the side closest to the charging port. Also, as others mentioned, when this releases it will go flying - mine did too.
Take note of how it’s oriented before you pop it loose - it only goes on one way (can’t be rotated 180 degrees)
When re-installing the bracket later, I inserted the side closet to the battery first (like the 2nd photo in Step 10 below), then rotated it down (pressing it down). It snaps back in place
The tape suggestion worked great! I used the suction cup, and the tape limited how far the display lifted once the snaps released. I’m sure I would have ripped the cable without this. No need to buy the iSlack to do this (if you have a suction cup)