I DVR'ed the most recent episode of the Americans on FX and the signal was scrambled, jumpy, and pixelated, so I deleted the recording and waiting a couple days for it to show up On Demand. Unfortunately, it's the same way On Demand.
You most likely have a signal issue. I find it highly unlikely that the broadcast and the OnDemand would both have the same issue. Pixilation and other similar issues are almost always a cable signal issue that needs to be corrected.