No idea if the validation schema of the sports channel is good enough and catches all cases with weird licensing restrictions of their live streams, but it works now and it's basically the same format as the one from the previous implementation, so I don't really care.
Streams were working fine, unless region blocked.
German IP address: not all inaccessible streams are marked as ones, and a short video with a region block screen is returned instead
$ ./script/test-plugin-urls.py ceskatelevize --metadata
:: https://ceskatelevize.cz/zive/art
:: 288p, 404p, 576p, worst, best
:: {'id': 'CH_6', 'author': None, 'category': None, 'title': 'ČT art'}
:: https://ceskatelevize.cz/zive/ch-28
:::: The stream is inaccessible
!! No streams found
:: https://ceskatelevize.cz/zive/ct1
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_1', 'author': None, 'category': None, 'title': 'ČT1'}
:: https://ceskatelevize.cz/zive/ct2
:::: The stream is inaccessible
!! No streams found
:: https://ct24.ceskatelevize.cz/
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_24', 'author': None, 'category': None, 'title': 'ČT24'}
:: https://decko.ceskatelevize.cz/
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_5', 'author': None, 'category': None, 'title': 'ČT :D'}
:: https://sport.ceskatelevize.cz/
:::: The stream is inaccessible
!! No streams found
$ ./script/test-plugin-urls.py ceskatelevize --metadata
:: https://ceskatelevize.cz/zive/art
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_6', 'author': None, 'category': None, 'title': 'ČT art'}
:: https://ceskatelevize.cz/zive/ch-28
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_28', 'author': None, 'category': None, 'title': 'I28'}
:: https://ceskatelevize.cz/zive/ct1
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_1', 'author': None, 'category': None, 'title': 'ČT1'}
:: https://ceskatelevize.cz/zive/ct2
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_2', 'author': None, 'category': None, 'title': 'ČT2'}
:: https://ct24.ceskatelevize.cz/
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_24', 'author': None, 'category': None, 'title': 'ČT24'}
:: https://decko.ceskatelevize.cz/
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_5', 'author': None, 'category': None, 'title': 'ČT :D'}
:: https://sport.ceskatelevize.cz/
:: 288p, 404p, 576p, 720p, 1080p, worst, best
:: {'id': 'CH_4', 'author': None, 'category': None, 'title': 'ČT Sport'}