Hello Erin. Thankyou for putting the time into your video and explaining speaker responses and listening windows. I'm listening and pause the video when I see points I would like to make as my memory is short. I put equal weight for 2 channel and HT application on my speakers.
1) I do agree with your premise that HT generally prefer to play louder than 2 channel guys.
2) I disagree with the premise that HT people do not require as smooth a listening window as 2 channel guys because we fall back to room correction facilities on AVRs. Like the name says, its a room correction facility and these correction schemes try to give the speakers a smooth flat in room response with respect to the LP (listener position). The better the directivity of a speaker, the more successful the correction facility has to overcome some weird anomalies. Nothing ruins a good movie faster than a poor quality soundtrack being delivered. Maybe its because I put equal weight for both HT and music.
3) Subwoofers are slowly making inroads into the 2 channel crowd and those who have incorporated sub will never go back without one. You already see the value in subs.
4) I would not purchase the speaker in your last example because it has a poor on axis response even though its off axes response is fairly linear. One may be able to EQ it but I listen to my music with no EQ.
Maybe I'm missing your points because of my listening criteria
but to me a good speaker should excel in both applications. Thanks again.