A brain zap is common withdrawal symptom of certain anti-depression and anti-anxiety drugs. A seemingly electrical pulse is felt to rush across the brain. Not painful but momentarily disorienting. A brain zap is usually not unpleasant and may be followed by a few seconds of slightly dizzy or even euphoric feeling.
When ever I watch DVDs on my cheap player, the movie always seems to have a little pause or brain zap right in the middle.