I just stumbled onto this thread as I have the same lights…
Feit Model 72031 - 48ft Color Changing LED Light Set…
Anyway, I looked up the FCC ID as you can see here: https://fccid.io/2AIH2RF20160226B
I got very excited since it shows Frequency Range 433.92-433.92 MHz. However, I also don’t pick up any codes on 433 MHz. My testing is done using https://github.com/ninjablocks/433Utils RFSniffer utility, which works for me testing transmitter remote control devices from Etekcity RF switches.
I also have decided to just put a switch in front of the Feit lights, but it sure seemed hopeful there for a moment. Perhaps RFSniffer is not the proper tool?