There are a few free solutions to record a long duration video call locally on your computer (including audio and video)
Chrome Browser
Screencastify is a free chrome plugin.
Mac
If you use a Mac you can use Quicktime to record.
Camtasia
You can record a Blitzz session with Camtasia that works in parallel. Then you can save it to your computer or local drive. Here's the link to a free trial of Camtasia.