Same issue here, but slightly different view and details.
I ordered a Panasonic TC-P50ST50 and accepted delivery Jan 28, 2013. I observed the "Netflix issue" (TV appears to lose sync or to insert one or more black frames each time Netflix changes their adaptive bit rate streaming to match my perceived Internet connectivity). Unfortunately for me, when streaming Netflix HD, Netflix needs something greater than 6Mbps for the best quality level, and my DSL DL is rated at ~6Mbps, max. So Netflix streaming HD continually toggles between "High HD" and "Medium HD", so the "blink" happens typically every few seconds.
As others have noted, the issue is not observed on most other streaming services (HuLu, YouTube, etc.), because (a) many are not streaming HD and (b) most are not using "adaptive birate streaming".
NOTE: I streamed Netflix HD for at least several months or more through a Panasonic Blu-Ray player (model DMP-BDT220) to an inexpensive Sony Bravia HDTV and never had this issue.
As a test, I moved the DMP-BDT220 to the new Panasonic TC-P50ST50 and the TV does NOT "blink" when Netflix streams through the Blu-Ray player, like it "blinks" when streaming directly to the TV. (Note... same Internet connectivity, same DSL modem, same Netflix adaptive streaming... same everything for these two tests, except in one instance streaming directly to the TV and in the other instance, streaming through the Blu-Ray player and then to the TV over HDMI).
In the 19 days since I received the TV:
(1) I Googled for this issue and found MANY references to this issue, including prior posts in this forum. Some references believe the problem to be caused by Netflix, while most agree the problem is the Panasonic TV.
(2) I emailed Panasonic technical support within 24 hours of receiving the TV, asking them about the issue, documenting the issue. Panasonic initially informed me that they believed the problem was that the TV was on my WiFi network and my WiFi AP was more than 10 feet (!) away from the TV. (Panasonic doesn't seem to understand that a 54Mbps WiFi network is constrained by the 6Mbps DLS link.) I repeated the test with the TV wired (ethernet) to my DSL router/modem/AP... same "blink" issue. And there is NOTHING (?) on Panasonic's web site or in their TV documentation indicating that the WiFI Access Point must be within 10 feet of the TV.
(3) I've since opened a formal ticket with Panasonic and have talked by phone to various levels of technical support at Panasonic during the past 19 days. Email support folks at panasonic cannot help any further, I'm told. Everything must be phone. Each time I've talked to Panasonic, they have confirmed (a) they have never heard of such an issue - which is difficult to believe, since I can google and find many, many references to this issue, (b) they confirm Netflix's assertion that the TV should NOT flicker or blink when netflix changes their bitrate and (c) they cannot explain why the flicker occurs when Netflix streams directly to the TV but does not occur when netflix streams through an intermediate device, such as a Panasonic Blu-Ray player.
(4) Most recently, Panasonic escalted this to their "engineering department", with a promise to contact me by next Wednesday, 5pm eastern, Feb 20, 2013.
Note: Panasonic customer service has been... less than stellar, let's say. At a minimum, I expect to be contacted by the date they tell me. yet, I'm sensing a trend... is this actually typical of Panasonic customer service or is my experience abnormal?
* Sunday, Feb 3 - opened case with Panasonic. Promised someone would contact me by Wed, Feb 6. yet, not one contacted me.
* Thur, Feb 7, I phoned Panasonic for status and was told they "mis routed" my case, so no one would EVER have phoned me. But they promised they would "escalate" and someone coulwd contact me by Saturday, Feb 9.
* No one contact me by noon, Sat, Feb 9, so I phoned Panasonic for a status update. I was promised Panasonic would contact me by close-of-business that same day! Yet, no one contacted me.
* Monday, Feb 11, I contacted Panasonic for a status update. I was promised someone would contact me by Wed, Feb 13, 5pm central. Yet, no one contacted me.
* Wednesday, Feb 13, 6pm, I phoned Panasonic for a status update. I I was promised someone will contact me by next Wednesday, Feb 20, 5pm eastern (4m central). So I wait, not knowing if this is a Panasonic stall tactic, hoping I'll tire of pursuing the issue. (They don't know me...). NOTE... Feb 20 will be "day 24" since I received the TV, nearing my "30 day" window of opportunity to choose to return the TV. (I don't "want" to return the TV, but have saved all packaging, just in case I decide Panasonic customer support has left me no other option.)
Of course, one concern is that the TV may h ave other "hidden problems" that I've not yet discovered, since Panasonic seems to be in denial about a problem I so easily discovered and that has been so widely reported on the Internet.
At a minimum, I expected Panasonic customer service to contact me by the promised dates and provide an update, even if just to say they "need more time". But I have not once received that simple courtesy.
SO MY QUESTION for members of this forum...
I purchased this directly from Panasonic online. Panasonic online has a 30 day return policy. If Panasonic customer support continues with these delays and I reach day 29-30, should I just return the TV (on principle, as much as anything) and perhaps buy a LG or Samsung (or other?) Plasma? How does other (LG, Samsung, etc.) Customer Service, compare?
I know I can "work around" the TV issue by using a Blu-Ray player, or similar, but on principle, I should not need to "work-around" an issue on a brand new TV. Yet, I do like the picture quality, brightness, etc... would similar priced Plasma TVs from competitors provide equally pleasing picture quality?