What several of these videos show is the first signs of "melodeonisation" -- a tune being changed (bodged?) to make it easier to play on the box, or to fit in with the basses.
Or at least, according to the version in my head that used to be played by Northumbrian fiddlers...
As with many traditional tunes, there will be at least as many variants as players - probably more, as I suspect few of us play any tune EXACTLY the same twice. Published - or indeed unpublished manuscript - versions of tunes are only "correct" in the sense that they represent one person's interpretation of how one musician played that tune once on one particular day. I seriously doubt that all "Northumbrian fiddlers" played any tune identically on the same day and playing together, let alone individually weeks, months and years apart. I'm sure you have a variant in your head - as have I, as have most of us; but that's just what it is - a variant. Yours may not be the same as mine, or as XYZ's from Little Piddlington, but they're all equally valid. That's the nature of traditional music, I'm afraid.......
Graham