Good point.
This is with OpenElec and Kodi. It was actually 480p video.

I just did an experiment decoding x265 on the Rasp Pi 2.

Decoding 480p video put all four cores on average at 50% load. I watched for 5 minutes and there were a dozen missed frames.

Decoding the same video encoded with x264 put all four cores on average at 10% load. There were no missed frames.