Adding audio as video - not working

I know this has been discussed quite a lot both here and on FB, but I’d like to give it a go:
I’d very much like to add an audio track for a project. According to the manual, this is possible with the Sibelius-esque workaround of creating a (audio only) video and then importing this to a project. But It seems impossible to add video of any kind to Dorico. Mov, Avi should be possible, but no one will be added, only error messages, or messages of wrong file type. Which should not be the case. I do have enough bars for the video duration, everything should be correct.

I run 3.1.10, on a Mac os x 10.15.3.

What am I missing? Any reply is appreciated.

Dorico supports a number of video formats encapsulated in mov or avi or whatever file encapsulation. You should find those formats in the docs…
10s of search in google :

Thanks Marc

I posted this because I have read that manual page you sent me (among others), thanks though. I am asking for help as to what other things than is mentioned in the manual could bug my attempt to add video. I am using those kinds of files (I’ve tried different variants of AVI and MOV), but Dorico seems to do not want any file added. Is there any thing I should do beforehand of adding, properties, size, length, anything??

For information, I get this message after Dorico let me pick a .mov-file from desktop (via right-click on flow in set-up mode, video->attach):
“The video format is not supported.”

.mov is not a video format, it is an encapsulating format.
If you can, check which codecs are being used inside the .mov file.