this video's cool but it's got some problems. the metering and visualizations of how compression works are awesome, but there's a lot that's sonically wrong here. for one thing, the compressor settings on the voiceover are not actually great at all, even as the narrator demonstrates the compressor's effectiveness--their release time is too long, resulting in what you can hear as an very overcompressed adr track. i thought this must have been a fluke but then during the demo with the full song multitrack when they turned the compressor on, you can clearly hear the snare pumping too much and a very un-natural sound throughout the entire mix.
tl:dr; this video shows good visualizations of what compression does, but does a horrible example of actually using compression well