You can use third-party tools like DownSub or SaveSubs . Just paste the URL of the video, and they will extract the text files.
It seems you are looking to download a text file ("txt") related to an OTT (Over-the-Top) service, likely subtitles, a transcript, or perhaps a script. Download OTT txt
For platforms like YouTube, click the three dots ( ... ) below the video and select "Show transcript" to copy the text. You can use third-party tools like DownSub or SaveSubs