Download additional infos

[arminfuerst]

Checklist

• I'm reporting a feature request
• I've verified that I'm running youtube-dl version 2021.05.16
• I've searched the bugtracker for similar feature requests including closed ones

Description

Many sites provide additional material for each video, I'm thinking mainly about a thumbnail and some description. It would be great if those could be downloaded and named like the video.
Here is an example to illustrate what I mean:
When I download https://tvthek.orf.at/history/Das-kann-man-selbst-tun/13557959/Alte-Sorten-Apfelvielhalt-erhalten/14079894 I get the file "Alte Sorten - Apfelvielhalt erhalten-14845389.mp4".
I'd like to have two additional files:

• "Alte Sorten - Apfelvielhalt erhalten-14845389.txt"
• "Alte Sorten - Apfelvielhalt erhalten-14845389.(jpg | png | ...)"

The source of the image in this example could be https://api-tvthek.orf.at/uploads/media/segments/0114/96/200daba7fdd975513ef831fb2a95fd7a2e649eba.png (e.g. from <meta property="og:image" ... - but there are other possible sources in this case).
The source of the text could be the description (e.g. from <meta property="og:description" ... - there are also additional sources in this case).

The example provided for ORF TVThek is just one example, this is also possible with a lot of other sites (3sat.de, tvnow.de, zdf.de, ...)