Buzzing noise after project completion!

I had about a 700 MB AVI file of an old classic science fiction movie. I authored and burned it in TMPGEnc, just like I have been doing steadlily for awhile now.

Upon completion, I always check my work and when I hit play on this, there was a constant buzzing noise throughout the whole video. I even tried another blank DVD and it still did the same thing.

It's no big deal, I've already found a replacement for it, but I'm just wondering what the heck it is I ran into. Could there have been some copyright protection embedded in this thing or was it probably just that the file had some quirks?