The RNG2 seed 0xC987 gives a path where you can walk to Pewter City with 0 encounters. The movie starts from savestate with 0xC987 hacked into RNG2.
The path is faster than the path used in [2520] GBA Pokémon: FireRed Version by mkdasher in 1:44:17.34
To get the RNG2 seed 0xC987, you need to get the reseeding routine (called after the title screen) to roll 0x0A94.
See also: