Who is Beethoven’s “Immortal Beloved?” one video source and two text sources (reliable sources)

Write three letters (one for each source) to a student in the future who may use these resources for their research. In each letter, evaluate the validity of the source by answering the following questions:

What does the author or speaker say in regard to your musical mystery? What is their opinion?
How does the author or speaker use reasoning and evidence to back up their claims?
Is there any evidence the author or speaker cites that seems exaggerated or distorted?
How much do you trust this source?