According to today's BarBri lecturer, who repeated the point numerous times...federalism is "the limits we place on state and local governments because we have a national government" or, in another iteration, "We need to have limits on state and local governments."

That's only one insufficiently narrow side of the story - and a somewhat strange starting point for the topic.  It seemed so slanted and "off" that I stated out loud that the definition wasn't right.

Federalism, even with the Supremacy Clause, is a broader construct relating to the diffusion or balancing of power between state and national governments - and includes limits on the powers of the federal government itself.

ADDED: Now, the lecturer has stated that "No limits exist on Congress' ability to delegate legislative power."  That's incorrect - Panama and Schecter, cases from the 1930s, place limits on Congress' abilities to delegate authority to the Executive.

That's after he opened the section about Legislative powers with "Basically, Congress can do whatever it wants - unless it interferes with individual liberties."  So much for any reference to a limited national government with enumerated powers.