Gotta say nothing in that recording sounds especially unusual to me (though I seem to have a thing for 200k mile cars so I might just be used to more noises). Injector seals tend to make a much more periodic "pfft pfft pfft pfft pfft" noise because the most pressure escapes on the power stroke of the faulty cylinder so I very much doubt it's injector seal - you can hear the noise about 30s into this video
https://www.youtube.com/watch?v=yCNMDJlOg4I