DirectTV shuts off for the safety video, so that shouldn't be an issue.

I've found that most crews are attentive to the volume, particularly because it can be too loud or too soft during taxi.

Although it's true that I know how to button and unbuckle a seatbelt, I watch the demo every time. Perhaps it's wishful thinking, but I always hope that it encourages others to pay attention.

Although I probably know much of it word-for-word in English, Spanish, German, and Hebrew.

There are always little reminders: don't use the aft doors when ditching on some planes versus don't use the overwing exits on others. I try to remember where additional rafts are located, or that some aircraft have dual slides while others have single slides.

I did once point out to a Delta 777 flight attendant that the video was not playing. She didn't care, and she had some sort of dismissive response.

I actually prefer having flight attendants stand in the aisles. Although they probably feel awkward, there is an implicit message that one should be paying attention.