Improve demo video

[clange]

Feedback from @PhilippMayr and @johanneswilm based on Open Science experience

Technical description is absolutely fine

Possible improvements:

• need better sound quality / better microphone
• transitions are a matter of taste
• optional: show face of speaker in the beginning (looks more professional)

[johanneswilm]

Since the video was made, the handling on the part of the reviewer/editor is slightly different, because the links are now in the file sections rather than the title. So for that reason it should probably be filmed again when it is being renewed anyway.