Very cool idea. Seems like an awful lot of rotating mass with the entire cylinder barrel spinning. This is actually similar to how many hydraulic pumps work, there does tend to be a lot of wear on the port interface surfaces though.
On a hydraulic pump, you end up with losses in pump output over time, which can be accounted for by oversizing. These losses in an IC engine would be much more problematic, resulting in losses in efficiency and increased emissions over time. They didn't get into much detail on the port arrangement but I think that will be the biggest hurdle to overcome.