The original video illustrates a specific mechanism for manipulating public opinion. This is still required to convince people that they live in a free society where their votes matter. This veneer of democracy is why substantial parts of US population go along with the system. Each party presents a set of policies and then people go to vote against the policies they think will hurt them the most.
The study implies how it’s actually done: purchased and paid for. That’s a flaw in any form of government; not some exclusive exploit towards democracy.
This is not a flaw in any form of government. It’s a flaw in capitalist societies that allow for huge amounts of inequality and private ownership of the media.