I use ZAP and similar tools (intercepting http proxies) on a daily basis when I do security testing. I don’t remember what the initial problems were that I was running into, so I couldn’t easily make a starter video. However there is a reason why there is no official video tutorials, and that is because most of the developers are busy developing the tool rather than writing documentation.
So far the best documentation are the questions asked in the user group and the issues raised on github. The search functionality of both is pretty good and most of my problems get solved by reading answers to other people’s problems.
The common question of “how do I use ZAP with tool X?” is usually pretty easily answered with “can you configure X to use an http proxy?”. After this the ZAP with default settings already does some passive scanning such as reading responses for stacktraces, error messages and oddities. This is the initial value one gets from using ZAP in combination with other testing frameworks.
Beyond this initial usage one can set scan policies, aggressiveness of the attacks and do, specify backend technologies to make attacks more relevant and accurate, etc.
ZAP is a complex tool (not necessarily complicated) because it supports almost any specific application security test case. There are recorded scripts, written scripts, and extensions that will do very specific and tightly scoped actions. Most of these are not useful for general testing or somebody who is just acquainted to the tool, but they might give an impression of a complicated interface.
Here’s some links to the user group, issues, and wiki. I’m also glad to answer questions and find out about the questions people have around ZAP.