I noticed that Starz was again showing "The Waterboy" tonight. So I recorded 3 minutes of it, mostly of high motion football game action. Then I watched it at 1/4 speed to look for compression artifacts, most notably pixelation & blocking.
I found 18 distinct examples, some of them lasting several frames. In one scene where the team was jumping up and down in the endzone, celebrating a victory, every single orange uniform was blocked. When paused I could see pixelated edges around every uniform number and around the edges of their orange uniforms against the green grass background. All detail on the uniforms, such as folds & creases in the cloth, was smeared.
I could play these scenes back and forth at any speed and all of the artifacts remained.
On scenes with low motion, the image was fine.
Again this is off of 61.5.
I immediately went to other channels and recorded fast motion scenes, played them in slow motion, and there were no artifacts. I tested HDNET, Discover HD, ESPN HD, RAVE, and GAMEPLAY.
Then I came back to Starz HD, recorded two more minutes, and found several more compression examples.
So it isn't my TV, nor is it a problem with all 61.5 channels, or the 622. At least not for MPEG2 channels. The problem is confined to Starz HD from 61.5. I can't test it from 129 to see if it might be due to Dish overly compressing it on 61.5.