Glitch is hard to define. To me it's music by machines, and the sound of those machines' errors, be they quiet and subtle or loud and noisy. It can also be represented visually, like some of the stuff at this site: beflix.com, although the guy has gotten increasingly involved in creating glitch art than capturing screens of real glitches. It's cool either way, I think, although I have a fascination with the anthropomorphized idea of a computer's brain misfiring like an emotion, and seeing what it looks like.
Also, I was talking about the whole album called Frame, but the track is great. I had a discussion some years ago with the artist, Dan Abrams, who told me that although people call his music "glitch", he prefers the term "microsound". So yeah, the definition is a bit ambiguous.