There are some quite obvious mistakes with the timing and spacing of the oars. It feels a bit like he is rowing in mud or something and then moving super fast back in the air. There is also some ugly mistakes with the arcs of them both right before it goes down into the water and in the water. The hands also goes out of their arcs as he reaches forward.
Oh well, hehe.. it was good fun to do. I want to do more of this in the future, and hopefully the next one will get better :)