Thank you for the helpful insights
I tried going to watch a video after the walk, and it worked not bad
As you can see in the picture, at least he's settled : he's not in his bed, and still close to the screen / speakers, but he's not attacking anything, not barking in distress to the images
I went safe on this one, and put some scientific YouTube videos (yes, I enjoy them, I'm that kind of a dork :D :D), so I guess there wasn't much trigger
On the next one, there may have been some, but I guess it was too noisy, and he was tired, so he went to sleep in another room, I guess in the office
We're nowhere near watching a whole movie with him around, but a video here and there, then an episode here and there, and maybe we'll get to the movie soon