Let’s be clear. A lame duck is one that has been shot, is still in flight, but is headed down. In politics, it refers to after a sitting representative loses an election (or term limit ends) but before before the term ends.

Obama was not a lame duck when Scalia died. McConnell et al redefined the term to suit their needs. As they will no doubt redefine it now.

He was just saying that the nomination should not happen during an election year and then he expands that he won't consider conservative nominees from the conservative i.e. different party president. It's just 4 minute video of several speech fragments, does not take long to watch and be informed.