ytdl_hook: fix default track for single format

Tracks are marked as default tracks based on what yt-dlp/youtube-dl
returns in the field `requested_formats`. The problem is that this field
only exists when there is more then one requested format.
So `ytdl-format=bestvideo+bestaudio` would have that field,
but `ytdl-format=bestaudio` would not,
leading to no tracks being marked as default tracks.

The requested formats can also be found under `requested_downloads`,
which exists regardless of the number of requested formats.
However when there is more then one requested format,
`requested_downloads` doesn't contain those formats directly and instead
has a field `requested_formats` that is identical to the other
`requested_formats`. Therefore use `requested_downloads` as a fallback
for when `requested_formats` doesn't exist.

0 files changed, 0 insertions, 0 deletions