I checked (running viperDNA 3.1.0 which is a 4.4 port from the One).
HDR (imaging, not video) works
1080p video works
720p 60fps video works
The phone uses the 700mhz block C LTE band.
What do you ran by HDR video? HTC feature HDR is an image process where the device takes multiple images at different capture rates (100, 400, 800, and 1600 I think) and combines the best of each to make a nice image.
Sent from my HTC6435LVW using xda app-developers app