After a bit more testing, that 5th strand's 2nd LED started flickering also randomly. Having used Processing initially, I thought it might be the screen capture software, so I tried Prismatik, Ambibox, but those 2 specific bullets still flickered randomly (not always).
I received your replacement strand about 5 days ago on the 27th of feb.
Installed it, watched the same tv show that had those 2 LED bullets flickering during some scenes and no flickering this time. Then I watched another movie to make sure it was really working flawlessly, and it did! I am so happy and relieved! So you were totally right, that strand was a defect.
Thank you so much for your AMAZING customer service!!!!! The advice, the replacement, the support, you guys are the BEST!!!!!

With your help, I was able to complete my adalight setup. Proud to own your products!!!!!