You can export existing subtitles/transcripts in the formats .VTT, .SRT and .TXT. You can also download the transcript (speech transcript) as .TXT. Select the relevant video in your MEDIA. Click on "Subtitles" at the bottom left and click on "Actions" for the subtitles you want to download. In the drop-down menu, you can select what you want to do.
The .TXT file will get you the pure text of the video. In the transcript, you get speaker-names and times as well.