I think you could convert the VTT file to a txt file and then load that into Msty desktop as a knowledge stack and then make queries about it. I can try it when I get home.
Discussion
I cleaned up the vtt file removing the timestamps and the author, but it seems that Llama3.1-8B cannot handle a 100KB file, it's too much for its 128K token context window.
It's a shame.