thats digital for you.
its either there, or its not.
in your case, its not.
somewhere, either on the tape itself, or during the capture from tape to computer, the digital information got messed up.
if its on the tape, you can chalk this one up to "youre screwed", as in you cant fix it.
what im seeing is the digital equivalent of the wavy/static/odd-coloring from a worn/ripped/crinkly VHS tape.