shown is far more common. "Showed" is past tense, as in "I showed the book to a friend." "Shown", is past perfect tense, it is opinion

Sayed is correct. Examples: I showed my mom my test. I had shown my test to my mom It's based on timing.

In passive, you use past participle. Showed is past tense and shown is past participle.

This verb can be used as both irregular and regular verb.Shown is the verb3 form of irregular verb.Showed is used either.This sentence is in Passive Voice. I was not shown in the video.