I typed in the hex from the last video, also. You can get the exact publish time by using Google's API explorer and directing it to the channel (channel activities api). The thing is, though, that the published date doesn't change if you change the video name. I uploaded a video with "Original title" and then changed it to "changed title" and all other meta data stayed the same.
We cannot be sure the title wasn't changed, honestly. Unless it's archived somewhere, the titles will change and the date the video is published won't change, and there isn't any other obvious meta data that will reveal that the title has changed.
This isn't the case, unfortunately.
Video posted: 2018-04-19T03:30:34.000Z
That's UTC, so converting the time to EST gives us: 11:30 PM EST.
Qanon's post was at 9:46 PM EST