I like the approach - might try it out - even i need to look at two screens at the same time ;) Maybe consider to have the app in a pop-out window, which I could overlay on my Netflix browser tab?

One thing I noticed, Query Strings contain the SRT filename, indicating the content could come from an unofficial, pirated source, such as "Se7en.1995.REMASTERED.1080p.BluRay.6CH.ShAaNiG.srt" ...