BarakAllāhu Feek, It is a summarised title for the whole speech of the Shaykh رحمه الله, abandoning the sunnah of the Nabī ﷺ and adapting the speech of someone other than him ﷺ as ruling in the religion.
BarakAllāhu Feekum, watch the video again akhī the Shaykh explains what is meant, it means leaving off the hukm of the Nabī ﷺ and following someone else's hukm, doesn't mean leaving off a sunnah that you know is a sunnah like for example you know 2 rak'ah before fajr is sunnah but you don't perform it, this is of course not shirk, and the same with the example you've mentioned, rather it means that you knowing the sunnah and the speech/command of the Nabī ﷺ is so and so but leaving it for the speech of someone other than the Nabī ﷺ and following that instead, like how some extreme blind followers of fiqh madhhabs do, this is what is being addressed by the Shaykh رحمه الله, i hope it clarified your question