Intermittent pixel distortion



So, I have a decade old 42" panasonic plasma 720p/1080p-ready TV myself which shows everything I stream beautifully. I've been looking to upgrade to a bigger screen, but I'm worried about a phenomenon I see at my sister's house. She has a 55" Samsung UE55HU6905UXXE model that doesn't stream my Plex shows well at all.

What happens is, that most of the time it looks very good, but every 5-10 seconds the image "tears" a bit, and feels like a hardware based lag or processing issue. The connection is good, and there's no buffering ever, and it plays directly without transcoding.

Could it be the thing called "200 Clear Motion Rate" ? Not seen that on newer TVs.

I would very much like to avoid this pixel tearing issue when I upgrade my TV. What should I focus on to avoid it? It's very slight, but enough that it annoys me and I'm left sitting waiting for it to happen.

Nearly all my shows are 720p/1080p and everywhere between 3 and 10K bitrate rips. When I get a 4K I will slowly start the ascend to higher bitrates and resolutions.