It was discovered that cutscene movement is possible in more scenes than the ones previously mentioned (elevators on M4, M5, M7, M14, M12 Geryon defeat, M17 spike room). The reason this could be relevant is not just being able to save some time moving, but if the IGT doesn't run during these scenes, ILs will be heavily affected by this. The full list (not including possible ones in secret missions or areas not relevant to speedruns) is this:

M3

After activating wheel (blue door hand disappears) scene

M4

Chamber of Echoes, Living Statue Room Enigma pre and post scene, elevator going up scene, Incandescent Space pre and post scene, Chamber of Echoes scene, Endless Infernum 1st & 2nd scene, Gigapede enter & defeat scene

M5

Post Bloodgoyle scene, Jester pre and post scene, Giantwalker Chamber post Jester, post Astronomical Board scene, using Vajra scene, pre & post Living Statue Room scene, using Soul of Steel scene, elevator wheel activation scene, elevator going up scene, A&R combination scene

M6

Trial of the Warrior pre and post scene, Artemis scene

M7

The Divine Library pre and post scene, Tranquil Souls pre and post scene, elevator going down & up scenes, Chamber of Echoes fire door scene, Cursed Skull Chamber wheel activation scene & pre and post scene, Tranquil Souls post scene, Peak of Darkness scene

M8

Tusk scenes, Gigapede scenes, Ignis Fatuus pre and post scene, Leviathan pre scene

M9

Rotating Bridge scene, Provisions Storeroom pre and post scene, Subterranean Garden pre and post scene, Subterranean lake scene, Provisions Storeroom (2) pre and post scene

M10

Stone Mask scene, Rounded Pathway pre and post scene, Provisions Storeroom pre and post scene, Rotating Bridge scene

M11

Altar of Evil Pathway scene, Altar of Evil pre and post scene

M12

Torture Chamber scene, Altar of Evil pre and post scene, Marble Throughway pre and post scene, Rotating Bridge scene, Geryon defeat scene

M13

Effervescence Corridor pre and post scene, Vestibule puzzle solve scene, Orihalcon scene

M14

Elevator going up scene, Altar of Evil pre and post scene, Hell's Highway scenes

M15

Upper Subterranean Garden post scene, Gears of Madness pre scene, Altar of Evil Pathway pre scene

M16

Chamber of Sins post scene, Living Statue Room pre and post scene, Waking Sun Chamber Golden Sun scene & pre and post

M17

God-cube Chamber scene, Trial of Wisdom pre and post scene, Trial of Skill pre scene Skull Spire pre and post-scene, Doppelganger post scene

M18

Chess boss pre and post scene, post boss scenes

M19

Room of Fallen Ones pre and post scene, Nirvana of Illusions pre and post-scene, Infinity Nirvana pre and post-scene

A link to this thread will be included in the rules for convenience's sake.