Political economy became very interesting post-2008 (to myself), and lots of discussion in this space is conducted in the (recorded) public sphere, due to collaboration and discussion between universities, policy institutes, central banks, (inter-)governmental entities, and independent analysts.
This expanded with COVID, due to:
Often I wanted to cover this material during {commuting, cleaning, cardio, cooking, DIY} etc. That is, I wanted to make use of any surplus attention whilst doing routine tasks, or to turn 'grunt time' into useful time.
During these kinds of activities, I may not have fully-free hands or eyes to hold/watch a mobile device, but I still want to save (what I perceive to be) the most salient segments. These segments might range from a substantial chunk of argument or exposition (that needs re-viewing to understand it better), to a lightweight reference for further exploration of a topic.
In either case, there was need for a hands-free1 analogue of a highlighter for audio and video.
tl;dr this is all Mark Blyth's fault.