Some of these lines seem to be difficult to trigger. Specifically in the Buff and Heal categories they only happen with a touch or melee spell and they have to be standing far enough away from the target that they have time to speak while running over. Even then when lines do play they seem to all be the neutral relations lines, not these really sweet ones. Hopefully its a bug that will be fixed some day.
Examples:
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Similarly the Help Immobilized and Downed lines seem to sometimes not play from the right relations category either. (In my current game a romanced Astarion gives neutral lines, and my Tav gives lines as if he's in love with everyone in the camp.)
This is as of yet speculative and untested but the speak-to lines at the end of the video are likely only going to be heard in an Origin run, since a controlled companion can't just start a conversation with a Tav/Durge PC character by clicking. But, I figure that one could imagine that their inner thoughts might be similar no matter the romantic partner c:
00:00 Buffing - Out of Combat
00:13 Buffing - In Combat
00:29 Buffing - While Sneaking
00:43 Healing - Out of Combat
00:55 Healing - In Combat
01:07 Healing - While Sneaking
01:19 Help Immobilized - Out of Combat
01:40 Help Immobilized - In Combat
02:01 Help Immobilized - While Sneaking
02:23 Help Unconscious - Out of Combat
02:43 Help Unconscious - In Combat
03:04 Help Unconscious - While Sneaking
03:25 Speak to
03:47 Speak to While Sneaking