No offence meant at all. After all, I think I'm probably playing my uke like a banjo right now! I meant to be a bit tongue in cheek, but the smiley has come out so tiny I can't see that one eye is winking even though I know it is.
On a more technique oriented note, most clawhammer players wouldn't play the double time run of notes you played towards the end with fast sequential downstrokes, as it breaks up the rhythm. It would normally be a combo of hammer ons, pull offs, drop thumbing and cross string playing, and they would retune if necessary just to make that passage easier (or more likely would miss out a couple of the notes and just thumb the high string instead, and let people's ears make it sound right). However, a hundred years ago people played like that all the time. Nowadays it's called stroke style or minstrel style. Less common, but perfectly fine.
I think you do have a problem with your thumb on the high string though. It looks to me as though you are actively plucking it downwards when you play it, which slows you down and will cause problems when you start drop thumbing to play the other strings. You should try and just lightly pluck the high string when you lift your hand UP off the string. The action is, bizarrely, a bit like a uke downstroke with a twist of the wrist doing it. Some folks do bend their thumb when they want to play the high string, but that's just so they make contact, the pluck is still light and upwards. If you can crack that your playing will get faster.a d a lot smoother, and the world of syncopated drop thumbing will be yours for the taking