Interesting "happening", for sure. Anyone w/ connections to the VFW should ask why this song was played. My guess is it was POTUS' (or his staff's) request. If we could find out it was by request, then that would be another "Q proof".
As it touches so much on clock-related stuff, here's some observations:
The video above >>2269306 has a timestamp (LR corner). The RSB guys are based out of Auburn (AL), the convention was in Kansas City – both Central Time (CDT).
CBS had a tweet/video: twitter.com/CBSNews/status/1021801069012234240/video/1 stamped 09:55 (PDT) or 11:55 (CDT).
Would all work fine with the timestamp in the video, which then likely would be CDT.
Q's "From Sea to Shining Sea." was posted 10:45 (EST) or 11:45 (EDT) or 10:45 (CDT).
If that's all correct, then Q posted 1 hr 08 mins (or 01:07 give or take) before the song started at the convention.
From what I can read on his lips, POTUS first says "Thank you", followed by "Listen" (after the "plains of Texas"). Works well with putting his finger on his ear repeatedly. Think it's a word ending on "N". "S" (as in saying "Texas") would look different, also a "T" in the beginning would look different, I think.
It's a "listen" though, more pronounced like "lesson" (in the "e"/"i"), than the "i" in e.g. "mirror".
Wouldn't over-interpret (in terms of bow-like motion) his moves at "It's time we stand". Checking videos of him dancing (also the sword dance in SA), it would appear to me that it is his way of moving to music – with rhythmic motions of his head mostly, parts of shoulders/upper body and knees a bit (depending how engaged he's dancing).
He certainly emphasizes this part though – by touching ear again & pointing up with his finger.
I'd completely agree that there's three things emphasized (may have been more, as the camera shows audience at times): "Texas", "Sea to Shining Sea" & "It's time we stand and say […]".
So it makes sense to connect this to the tweets shown – even though deltas are not typical (i.e. 1, 5, 10, 15 etc) … but I might have to double-check that.