I think the glass was very smooth.
I would distort the image.
Some horizontal banding perhaps?
The value node has a driver. In the value node type in #frame this gives you the frame number. The multiply node gives the speed of the banding I found 4.7 to look lovely 
Those were the days!
Edit: I had a bit more fun with this
I added a bit of flicker and made the large bands increase contrast.
Now it is really starting to look like my old tele!
Sorry its a bit blurry, it is just a screen-cast + video compression.