Some websites with m3u streaming cannot be downloaded in a single youtube-dl
step, you can try something like this :
$ URL=https://www.arte.tv/fr/videos/078132-001-A/cosmos-une-odyssee-a-travers-l-univers/
$ youtube-dl -F $URL | grep m3u
HLS_XQ_2 m3u8 1280x720 VA-STA, Allemand 2200k
HLS_XQ_1 m3u8 1280x720 VF-STF, Français 2200k
$ CHOSEN_FORMAT=HLS_XQ_1
$ youtube-dl -F "$(youtube-dl -gf $CHOSEN_FORMAT)"
[generic] master: Requesting header
[generic] master: Downloading webpage
[generic] master: Downloading m3u8 information
[info] Available formats for master:
format code extension resolution note
61 mp4 audio only 61k , mp4a.40.2
419 mp4 384x216 419k , avc1.66.30, mp4a.40.2
923 mp4 640x360 923k , avc1.77.30, mp4a.40.2
1737 mp4 720x406 1737k , avc1.77.30, mp4a.40.2
2521 mp4 1280x720 2521k , avc1.77.30, mp4a.40.2 (best)
$ youtube-dl --hls-prefer-native -f 1737 "$(youtube-dl -gf $CHOSEN_FORMAT $URL)" -o "$(youtube-dl -f $CHOSEN_FORMAT --get-filename $URL)"
[generic] master: Requesting header
[generic] master: Downloading webpage
[generic] master: Downloading m3u8 information
[hlsnative] Downloading m3u8 manifest
[hlsnative] Total fragments: 257
[download] Destination: Cosmos_une_odyssee_a_travers_l_univers__HLS_XQ_1__078132-001-A.mp4
[download] 0.9% of ~731.27MiB at 624.95KiB/s ETA 13:13
....