thinking of a place
This is normal AI behaviour, they pick their moves a lot more randomly once they're out of PP for their strongest one. I've stalled so many Pokemon entirely out of PP with Gliscor, and they always mixed things up kinda erratically once their optimal move was out of PP, they didn't go cleanly down the list. I can't watch your video rn but assuming your plan was Roost stall Draco Meteor then switch-stall Dragon Rush and Earthquake, there's unfortunately no way to be sure it won't throw out a random Brick Break.Speaking of weird AI behavior I had this battle against a lead Salamence3.
Battle 119 against Roller Skater, Link: EV4G-WWWW-WW62-EL8U
After I stalled out it's Draco Meteor PP it constantly used Brick Break on my Talonflame ( which obviously hit my Mawile switch in ) despite it still had PP left on STAB Dragon Rush.
I generally believed AI would use the most damaging damage move against your active pokemon but it doesn't seem it was the case there.
And on the turn I stayed in with Talonflame he actually Dragon Rush'ed me. Some time I feel the AI select the move right after the player made the choice.
You can tell I was a little irritated at the end of the battle by how I used Mawile in the end, But well, I made sure to stall out Earthquake first.
Ironically a critical Earthquake is exactly what ended this streak.