Firefox 79 is run the same way as 78. You unpack the installer and modify firefox.exe via CCF Explorer. Go into the import table, select ntdll.dll and change the entry RtlQueryPerformanceCounter to NtQueryInformationProcess.
With YouTube, maybe it will help:
https://msfn.org/board/topic/181612-wip-windows-vista-extended-kernel/?do=findComment&comment=1184838
I haven't tried it yet.