Complaining about combat or traversal interrupting BG3. Given that it's an old game without any fast travel, BG2 isn't exactly known for being a speedy game. And there's a lot of backtracking to turn in quests, or buy/sell things given your limited inventory space for large chunks of the game. Not to mention, it's pretty infamous for "you must gather your party before venturing forth". BG1 especially you walk ungodly slow, and there's massive chunks of empty space across the many maps.
Both games also feature plenty of combat, with BG1 and BG2 both notably having actual random encounter mechanics built into it, which BG3 does not have. There's also a fair amount of sloggish combat where you're fighting hoards of low-level enemies. Some spells also have lengthy durations and persist outside of combat, and stun/paralyze effects are pretty common. You might just be standing around after a fight waiting for a hold person spell to wear off before you can continue playing.
To be fair, you can definitely argue combat in the older games is faster because it's real time with pause vs. turn based, but given Lily never seems to engage with the mechanics/his general complaints about games, I'm assuming the combat complaint is more along the lines of him bitching about the game daring to have gameplay.
Switching gears to...whatever the censorship video was about and Lily getting triggered, it's kinda weird that Lily's favorite video game seems to avoid this. For those not in the know, BG2 opens with you and your sister kidnapped and being tortured/experimented on. You eventually break free, but after the tutorial, your sister is arrested alongside your captor/abuser, which is all part of his plan. He takes over the prison, and continues to torture/experiment on your sister, to the point he literally removes her soul and she at multiple points comments about how empty she feels. Even before that, she's pretty clearly suffering some kind of PTSD in the tutorial levels, to the point she straight up runs off and leaves your party if she gets too damaged because she can't handle going back to being captured.
The early chapter cutscenes all involve her being captured and tortured, and throughout the early chapters you have dreams where she dies (sometimes by your hand). Given the limited graphics, it's not exactly a brutal display or anything, nor is the text particularly graphic, but the VA is definitely distressed. And they don't shy away from the fact that she's pretty miserable, it's very much meant to be the motivating factor for the early game. The writers also changed her intended death because they basically acknowledged it'd be too miserable if after all that you couldn't rescue her (IIRC, you were even supposed to kill her when she goes full slayer mode on you) Still, you'd think despite all that, given how sensitive and easily triggered Lily is, and how much Lily seems to despise series like Dragon Age for being "too dark" you'd think he'd have some triggering issues with BG2.
Why, it's almost like Lily is completely media illiterate, doesn't pay any attention to gameplay mechanics and stories and just focuses on the mod that allows him to ignore everything else and get into tickle fights with his sister.