This video provides an introduction to the concept of capacity as contained in the Mental Capacity Act 2005.
This session does not cover assessment of capacity in the context of Covid-19, but rather focuses on the key aspects of the law so as to help people feel legally confident. For more on how to apply the law in the adverse conditions applying at present, see this video.
The slides are here.
Boring but necessary caveat: nothing in this constitutes legal advice.