First Apple TV -- Video Flicker

I just received my first Apple TV. I purchased a refurnished model from the Apple Store. (Pretty excited to finally get one!)

After hooking it up, I started checking everything out. On some iTunes TV shows that I recently purchased, I noticed an occasional video flicker, almost as it it skips a couple of frames. It happens randomly, perhaps one flicker every 5-15 seconds. It happens on shows that I've already downloaded and stored on my iMac, so I'm pretty sure it's not a network latency issue. It also happens on other Apple TV channels too with varying degrees of frequency.

Here's my set-up:
Refurb'd Apple TV
27"iMac (three years old)
Time Capsule, within decent range to the Apple TV (wifi signal is good in the living room on my iPhone and iPad)
My internet speed is very fast, measuring in at 57 mb/s. (Comcast)

I really don't think network latency is an issue. Could it possibly be a flaw with the refurbished Apple TV? I'll call Apple in a day or two, but thought I would stop in here to see if I could gather any ideas.

Thanks!
Bryan

Thank you for both replies. I appreciate it!

I'm going to order a new HDMI cable and see if that changes anything. And unfortunately, hard-wiring my Apple TV isn't an option for me. But thanks for the idea as it's a good troubleshooting step.

In regards to the idea of wifi dropping out for a milli-second and causing a subsequent frame loss...I'm curious if anyone else experiences frame losses on a somewhat regular basis while running an Apple TV over wifi? I realize that every setup is different in regards to signal strength and interference, but I'd like to know what others are experiencing. ...Actually, I just realized that an Apple TV buffers the video, so a quick glitch in the wifi signal shouldn't have any effect right?

Thanks for everyone's inputs!
Bryan

They aren't foreign films. They're domestic films and shows downloaded from the iTunes show. Specifically, the North America series (Discovery) and other shows I'm watching on iTunes. Also,mom not streaming them from the Cloud...just streaming them from my iMac where they are stored locally.

Thanks for the ideas though. Keep 'em coming!

Bryan