So my new workflow is to use Piped to find a video, then copy the end of the link and type “yt-dlp <C-S-v>” in a terminal, wait for the video(s) to download, and open in mpv.
Why not just pass the YouTube link to mpv so you don’t have to wait for the video to download?
I’ve had this same situation happen to me before and my solution was to search -x instead of just x.
Windows 8.1 (~10 years) -> Xubuntu (a few months) -> Arch linux (present).
My guess is that sway checks sets the opacity when the window open, so when the first rule matches (app_id=.*) it skips all others, so maybe try putting the other 2 rules above the first one?
Sorry if my comment is incomprehensible, I’ve just woken up.
In my experience the video loads in a few seconds compared to the minutes it’d take for it to download, but I get your second point.