I tried it yesterday and succeeded. I used the firefox browser as I don't think it works on chrome as it's Youtube. I went to the firefox add-on(extension store) and got a youtube video downloader. The one that worked for me was "Easy Youtube Video Downloader Express" once it's added it's super easy to use just got to the episode on youtube and select this will be next to the subscribe button, click it and select the desired quality you want and download. Unfortunately, the max is 720p due to server limitations if I find a 1080p one I will let you know. After that download is done go here: https://www.opensubtitles.org/en/ssearch/sublanguageid-eng/idmovie-884577 . This page is for KO in subs download the one you desire. After the download opens the zip file. There will be an "srt" file in there. Rename that file to the name of your video download leaving the "srt". Then the video should play with the subs. I was using VLC video player.
this is the closest we've gotten to a kayi game, then again its unlicensed and an indie game: https://play.google.com/store/apps/details?id=com.umuro.ertugrulgazi&hl=en_GB&gl=US